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Test Results

18F/portfolios

Snyk’s security scan found the following vulnerabilities.
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Vulnerabilities

 24 via 116 paths

Dependencies

 57

Source

 GitHub

Commit

 bde3b284

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Severity
  • 12
  • 11
  • 1
Status
  • 24
  • 0
  • 0

high severity

Improper Handling of Unexpected Data Type

  • Vulnerable module: nokogiri
  • Introduced through: nokogiri@1.11.4, html-proofer@3.6.0 and others

Detailed paths

  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › nokogiri@1.11.4
    Remediation: Upgrade to nokogiri@1.13.6.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › html-proofer@3.6.0 › nokogiri@1.11.4
    Remediation: Upgrade to html-proofer@3.6.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jemoji@0.12.0 › html-pipeline@2.14.0 › nokogiri@1.11.4
    Remediation: Upgrade to jemoji@0.12.0.

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to Improper Handling of Unexpected Data Type due to incorrectly checking the types of arguments to various constructors in HTML4::SAX and XML::SAX, which causes a segmentation fault.

Remediation

Upgrade nokogiri to version 1.13.6 or higher.

References

Improper Handling of Unexpected Data Type vulnerability report

high severity

Improper Restriction of XML External Entity Reference ('XXE')

  • Vulnerable module: rexml
  • Introduced through: kramdown-parser-gfm@1.1.0, jekyll@4.0.1 and others

Detailed paths

  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to kramdown-parser-gfm@1.1.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll@4.0.1 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll@4.0.1.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll@4.0.1 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll@4.0.1.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-redirect-from@0.16.0 › jekyll@4.0.1 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-redirect-from@0.16.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-seo-tag@2.7.1 › jekyll@4.0.1 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-seo-tag@2.7.1.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-sitemap@1.4.0 › jekyll@4.0.1 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-sitemap@1.4.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jemoji@0.12.0 › jekyll@4.0.1 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jemoji@0.12.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-redirect-from@0.16.0 › jekyll@4.0.1 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-redirect-from@0.16.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-seo-tag@2.7.1 › jekyll@4.0.1 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-seo-tag@2.7.1.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-sitemap@1.4.0 › jekyll@4.0.1 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-sitemap@1.4.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jemoji@0.12.0 › jekyll@4.0.1 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jemoji@0.12.0.

…and 8 more

Overview

rexml is an An XML toolkit for Ruby.

Affected versions of this package are vulnerable to Improper Restriction of XML External Entity Reference ('XXE') via tree parser APIs like REXML::Document.new function. An attacker can cause the application to consume excessive resources by submitting specially crafted XML documents with many deep elements that have the same local name attributes.

Note:

This is only exploitable if a tree parser API is used to parse untrusted XMLs.

Remediation

Upgrade rexml to version 3.3.6 or higher.

References

Improper Restriction of XML External Entity Reference ('XXE') vulnerability report

high severity

Use After Free

  • Vulnerable module: nokogiri
  • Introduced through: nokogiri@1.11.4, html-proofer@3.6.0 and others

Detailed paths

  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › nokogiri@1.11.4
    Remediation: Upgrade to nokogiri@1.13.2.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › html-proofer@3.6.0 › nokogiri@1.11.4
    Remediation: Upgrade to html-proofer@3.6.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jemoji@0.12.0 › html-pipeline@2.14.0 › nokogiri@1.11.4
    Remediation: Upgrade to jemoji@0.12.0.

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to Use After Free via the ID and IDREF attributes, when using the xmlReader interface with validation or when a document is parsed with XML_PARSE_DTDVALID and without XML_PARSE_NOENT. This can lead to the value of ID attributes to not be normalized after potentially expanding entities in xmlRemoveID, which will cause later calls to xmlGetID to return a pointer to previously freed memory.

Remediation

Upgrade nokogiri to version 1.13.2 or higher.

References

Use After Free vulnerability report

high severity

Denial of Service (DoS)

  • Vulnerable module: nokogiri
  • Introduced through: nokogiri@1.11.4, html-proofer@3.6.0 and others

Detailed paths

  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › nokogiri@1.11.4
    Remediation: Upgrade to nokogiri@1.13.4.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › html-proofer@3.6.0 › nokogiri@1.11.4
    Remediation: Upgrade to html-proofer@3.6.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jemoji@0.12.0 › html-pipeline@2.14.0 › nokogiri@1.11.4
    Remediation: Upgrade to jemoji@0.12.0.

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to Denial of Service (DoS) via the xerces:xercesImpldependency, as its XML parser consumes excessive amount of resources when handling specially crafted XML document payloads due to an infinite loop.

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 nokogiri to version 1.13.4 or higher.

References

Denial of Service (DoS) vulnerability report

high severity

Heap-based Buffer Overflow

  • Vulnerable module: nokogiri
  • Introduced through: nokogiri@1.11.4, html-proofer@3.6.0 and others

Detailed paths

  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › nokogiri@1.11.4
    Remediation: Upgrade to nokogiri@1.16.5.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › html-proofer@3.6.0 › nokogiri@1.11.4
    Remediation: Upgrade to html-proofer@3.6.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jemoji@0.12.0 › html-pipeline@2.14.0 › nokogiri@1.11.4
    Remediation: Upgrade to jemoji@0.12.0.

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to Heap-based Buffer Overflow through the xmlHTMLPrintFileContext function in xmllint.c. An attacker can read memory contents that may contain sensitive data by triggering a buffer over-read condition.

Remediation

Upgrade nokogiri to version 1.16.5 or higher.

References

Heap-based Buffer Overflow vulnerability report

high severity

NULL Pointer Dereference

  • Vulnerable module: nokogiri
  • Introduced through: nokogiri@1.11.4, html-proofer@3.6.0 and others

Detailed paths

  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › nokogiri@1.11.4
    Remediation: Upgrade to nokogiri@1.13.9.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › html-proofer@3.6.0 › nokogiri@1.11.4
    Remediation: Upgrade to html-proofer@3.6.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jemoji@0.12.0 › html-pipeline@2.14.0 › nokogiri@1.11.4
    Remediation: Upgrade to jemoji@0.12.0.

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to NULL Pointer Dereference due to the usage of a vulnerable version of the bundled libxml2 package.

Remediation

Upgrade nokogiri to version 1.13.9 or higher.

References

NULL Pointer Dereference vulnerability report

high severity

Out-of-bounds Write

  • Vulnerable module: nokogiri
  • Introduced through: nokogiri@1.11.4, html-proofer@3.6.0 and others

Detailed paths

  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › nokogiri@1.11.4
    Remediation: Upgrade to nokogiri@1.13.4.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › html-proofer@3.6.0 › nokogiri@1.11.4
    Remediation: Upgrade to html-proofer@3.6.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jemoji@0.12.0 › html-pipeline@2.14.0 › nokogiri@1.11.4
    Remediation: Upgrade to jemoji@0.12.0.

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to Out-of-bounds Write via the zlib dependency which allows memory corruption when deflating if the input has many distant matches.

Remediation

Upgrade nokogiri to version 1.13.4 or higher.

References

Out-of-bounds Write vulnerability report

high severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: nokogiri
  • Introduced through: nokogiri@1.11.4, html-proofer@3.6.0 and others

Detailed paths

  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › nokogiri@1.11.4
    Remediation: Upgrade to nokogiri@1.13.4.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › html-proofer@3.6.0 › nokogiri@1.11.4
    Remediation: Upgrade to html-proofer@3.6.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jemoji@0.12.0 › html-pipeline@2.14.0 › nokogiri@1.11.4
    Remediation: Upgrade to jemoji@0.12.0.

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS) due to an expression that is susceptible to excessive backtracking when attempting to detect encoding in HTML documents.

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 nokogiri to version 1.13.4 or higher.

References

Regular Expression Denial of Service (ReDoS) vulnerability report

high severity

XML External Entity (XXE) Injection

  • Vulnerable module: nokogiri
  • Introduced through: nokogiri@1.11.4, html-proofer@3.6.0 and others

Detailed paths

  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › nokogiri@1.11.4
    Remediation: Upgrade to nokogiri@1.12.5.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › html-proofer@3.6.0 › nokogiri@1.11.4
    Remediation: Upgrade to html-proofer@3.6.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jemoji@0.12.0 › html-pipeline@2.14.0 › nokogiri@1.11.4
    Remediation: Upgrade to jemoji@0.12.0.

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to XML External Entity (XXE) Injection. Users of Nokogiri on JRuby who parse untrusted documents using any of these classes are affected:

  • Nokogiri::XML::SAX::Parse
  • Nokogiri::HTML4::SAX::Parser or its alias Nokogiri::HTML::SAX::Parser
  • Nokogiri::XML::SAX::PushParser
  • Nokogiri::HTML4::SAX::PushParser or its alias Nokogiri::HTML::SAX::PushParser.

CRuby users are not affected.

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>
<?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>
<?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 nokogiri to version 1.12.5 or higher.

References

XML External Entity (XXE) Injection vulnerability report

high severity

Directory Traversal

  • Vulnerable module: tzinfo
  • Introduced through: html-proofer@3.6.0 and jemoji@0.12.0

Detailed paths

  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › html-proofer@3.6.0 › activesupport@5.2.6 › tzinfo@1.2.9
    Remediation: Upgrade to html-proofer@3.6.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jemoji@0.12.0 › html-pipeline@2.14.0 › activesupport@5.2.6 › tzinfo@1.2.9
    Remediation: Upgrade to jemoji@0.12.0.

Overview

Affected versions of this package are vulnerable to Directory Traversal. TZInfo::Timezone.get fails to validate time zone identifiers correctly, allowing a new line character within the identifier. With Ruby version 1.9.3 and later, TZInfo::Timezone.get can be made to load unintended files with require, executing them within the Ruby process.

This could be exploited in, for example, a Ruby on Rails application using a vulnerable version of tzinfo, that allows file uploads and has a time zone selector that accepts arbitrary time zone identifiers.

Details

A Directory Traversal attack (also known as path traversal) aims to access files and directories that are stored outside the intended folder. By manipulating files with "dot-dot-slash (../)" sequences and its variations, or by using absolute file paths, it may be possible to access arbitrary files and directories stored on file system, including application source code, configuration, and other critical system files.

Directory Traversal vulnerabilities can be generally divided into two types:

  • Information Disclosure: Allows the attacker to gain information about the folder structure or read the contents of sensitive files on the system.

st is a module for serving static files on web pages, and contains a vulnerability of this type. In our example, we will serve files from the public route.

If an attacker requests the following URL from our server, it will in turn leak the sensitive private key of the root user.

curl http://localhost:8080/public/%2e%2e/%2e%2e/%2e%2e/%2e%2e/%2e%2e/root/.ssh/id_rsa

Note %2e is the URL encoded version of . (dot).

  • Writing arbitrary files: Allows the attacker to create or replace existing files. This type of vulnerability is also known as Zip-Slip.

One way to achieve this is by using a malicious zip archive that holds path traversal filenames. When each filename in the zip archive gets concatenated to the target extraction folder, without validation, the final path ends up outside of the target folder. If an executable or a configuration file is overwritten with a file containing malicious code, the problem can turn into an arbitrary code execution issue quite easily.

The following is an example of a zip archive with one benign file and one malicious file. Extracting the malicious file will result in traversing out of the target folder, ending up in /root/.ssh/ overwriting the authorized_keys file:

2018-04-15 22:04:29 .....           19           19  good.txt
2018-04-15 22:04:42 .....           20           20  ../../../../../../root/.ssh/authorized_keys

Remediation

Upgrade tzinfo to version 0.3.61, 1.2.10 or higher.

References

Directory Traversal vulnerability report

high severity

Stack-based Buffer Overflow

  • Vulnerable module: nokogiri
  • Introduced through: nokogiri@1.11.4, html-proofer@3.6.0 and others

Detailed paths

  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › nokogiri@1.11.4
    Remediation: Upgrade to nokogiri@1.18.3.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › html-proofer@3.6.0 › nokogiri@1.11.4
    Remediation: Upgrade to html-proofer@3.6.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jemoji@0.12.0 › html-pipeline@2.14.0 › nokogiri@1.11.4
    Remediation: Upgrade to jemoji@0.12.0.

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to Stack-based Buffer Overflow in the xmlSnprintfElements() function. An attacker can overwrite out-of-bounds stack memory with XML NCName data by supplying a malicious XML document or malicious DTD.

This vulnerability is similar to the previously reported and patched (CVE-2017-9047)[https://security.snyk.io/vuln/SNYK-UNMANAGED-LIBXML2-3004044].

Remediation

Upgrade nokogiri to version 1.18.3 or higher.

References

Stack-based Buffer Overflow vulnerability report

high severity

Use After Free

  • Vulnerable module: nokogiri
  • Introduced through: nokogiri@1.11.4, html-proofer@3.6.0 and others

Detailed paths

  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › nokogiri@1.11.4
    Remediation: Upgrade to nokogiri@1.18.3.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › html-proofer@3.6.0 › nokogiri@1.11.4
    Remediation: Upgrade to html-proofer@3.6.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jemoji@0.12.0 › html-pipeline@2.14.0 › nokogiri@1.11.4
    Remediation: Upgrade to jemoji@0.12.0.

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to Use After Free in the xmlSchemaItemListAdd() function in xmlschemas.c, which is exploitable by supplying a malicious .xsd schema for validation. it may also be exploitable when an xsd:keyref is provided in combination with recursively defined types that have additional identity constraints, for validation against a non malicious schema.

Remediation

Upgrade nokogiri to version 1.18.3 or higher.

References

Use After Free vulnerability report

medium severity

Denial of Service (DoS)

  • Vulnerable module: rexml
  • Introduced through: kramdown-parser-gfm@1.1.0, jekyll@4.0.1 and others

Detailed paths

  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to kramdown-parser-gfm@1.1.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll@4.0.1 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll@4.0.1.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll@4.0.1 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll@4.0.1.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-redirect-from@0.16.0 › jekyll@4.0.1 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-redirect-from@0.16.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-seo-tag@2.7.1 › jekyll@4.0.1 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-seo-tag@2.7.1.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-sitemap@1.4.0 › jekyll@4.0.1 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-sitemap@1.4.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jemoji@0.12.0 › jekyll@4.0.1 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jemoji@0.12.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-redirect-from@0.16.0 › jekyll@4.0.1 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-redirect-from@0.16.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-seo-tag@2.7.1 › jekyll@4.0.1 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-seo-tag@2.7.1.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-sitemap@1.4.0 › jekyll@4.0.1 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-sitemap@1.4.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jemoji@0.12.0 › jekyll@4.0.1 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jemoji@0.12.0.

…and 8 more

Overview

rexml is an An XML toolkit for Ruby.

Affected versions of this package are vulnerable to Denial of Service (DoS) via the REXML gem, when parsing an XML document that has many specific characters such as whitespace character,>] and ]>.

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 rexml to version 3.3.3 or higher.

References

Denial of Service (DoS) vulnerability report

medium severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: rexml
  • Introduced through: kramdown-parser-gfm@1.1.0, jekyll@4.0.1 and others

Detailed paths

  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to kramdown-parser-gfm@1.1.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll@4.0.1 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll@4.0.1.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll@4.0.1 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll@4.0.1.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-redirect-from@0.16.0 › jekyll@4.0.1 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-redirect-from@0.16.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-seo-tag@2.7.1 › jekyll@4.0.1 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-seo-tag@2.7.1.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-sitemap@1.4.0 › jekyll@4.0.1 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-sitemap@1.4.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jemoji@0.12.0 › jekyll@4.0.1 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jemoji@0.12.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-redirect-from@0.16.0 › jekyll@4.0.1 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-redirect-from@0.16.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-seo-tag@2.7.1 › jekyll@4.0.1 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-seo-tag@2.7.1.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-sitemap@1.4.0 › jekyll@4.0.1 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-sitemap@1.4.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jemoji@0.12.0 › jekyll@4.0.1 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jemoji@0.12.0.

…and 8 more

Overview

rexml is an An XML toolkit for Ruby.

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS) due to the usage of insecure regular expressions in CHARACTER_REFERENCES. This vulnerability can be exploited when parsing XML content containing numerous digits between &# and x...; in a hex numeric character reference (&#x...;).

By supplying specially crafted XML documents, an attacker can cause the application to consume excessive resources.

Note:

This vulnerability doesn't affect Ruby 3.2 or later.

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 rexml to version 3.3.9 or higher.

References

Regular Expression Denial of Service (ReDoS) vulnerability report

medium severity

Uncontrolled Resource Consumption ('Resource Exhaustion')

  • Vulnerable module: rexml
  • Introduced through: kramdown-parser-gfm@1.1.0, jekyll@4.0.1 and others

Detailed paths

  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to kramdown-parser-gfm@1.1.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll@4.0.1 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll@4.0.1.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll@4.0.1 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll@4.0.1.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-redirect-from@0.16.0 › jekyll@4.0.1 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-redirect-from@0.16.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-seo-tag@2.7.1 › jekyll@4.0.1 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-seo-tag@2.7.1.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-sitemap@1.4.0 › jekyll@4.0.1 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-sitemap@1.4.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jemoji@0.12.0 › jekyll@4.0.1 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jemoji@0.12.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-redirect-from@0.16.0 › jekyll@4.0.1 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-redirect-from@0.16.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-seo-tag@2.7.1 › jekyll@4.0.1 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-seo-tag@2.7.1.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-sitemap@1.4.0 › jekyll@4.0.1 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-sitemap@1.4.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jemoji@0.12.0 › jekyll@4.0.1 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jemoji@0.12.0.

…and 8 more

Overview

rexml is an An XML toolkit for Ruby.

Affected versions of this package are vulnerable to Uncontrolled Resource Consumption ('Resource Exhaustion') via the SAX2 or pull parser API. An attacker can cause the application to consume excessive resources leading to a denial of service by submitting specially crafted XML documents that exploit entity expansions.

PoC

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE member [
  <!ENTITY a "&b;&b;&b;&b;&b;&b;&b;&b;&b;&b;">
  <!ENTITY b "&c;&c;&c;&c;&c;&c;&c;&c;&c;&c;">
  <!ENTITY c "&d;&d;&d;&d;&d;&d;&d;&d;&d;&d;">
  <!ENTITY d "&e;&e;&e;&e;&e;&e;&e;&e;&e;&e;">
  <!ENTITY e "&f;&f;&f;&f;&f;&f;&f;&f;&f;&f;">
  <!ENTITY f "&g;&g;&g;&g;&g;&g;&g;&g;&g;&g;">
  <!ENTITY g "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx">
]>
<member>
&a;
</member>

Remediation

Upgrade rexml to version 3.3.3 or higher.

References

Uncontrolled Resource Consumption ('Resource Exhaustion') vulnerability report

medium severity

Use After Free

  • Vulnerable module: nokogiri
  • Introduced through: nokogiri@1.11.4, html-proofer@3.6.0 and others

Detailed paths

  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › nokogiri@1.11.4
    Remediation: Upgrade to nokogiri@1.15.6.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › html-proofer@3.6.0 › nokogiri@1.11.4
    Remediation: Upgrade to html-proofer@3.6.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jemoji@0.12.0 › html-pipeline@2.14.0 › nokogiri@1.11.4
    Remediation: Upgrade to jemoji@0.12.0.

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to Use After Free via the xmlTextReader module. An attacker can cause denial of service by processing crafted XML documents with DTD validation and XInclude expansion enabled.

Remediation

Upgrade nokogiri to version 1.15.6, 1.16.2 or higher.

References

Use After Free vulnerability report

medium severity

Cross-site Scripting (XSS)

  • Vulnerable module: activesupport
  • Introduced through: html-proofer@3.6.0 and jemoji@0.12.0

Detailed paths

  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › html-proofer@3.6.0 › activesupport@5.2.6
    Remediation: Upgrade to html-proofer@3.12.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jemoji@0.12.0 › html-pipeline@2.14.0 › activesupport@5.2.6
    Remediation: Upgrade to jemoji@0.12.0.

Overview

activesupport is a toolkit of support libraries and Ruby core extensions extracted from the Rails framework.

Affected versions of this package are vulnerable to Cross-site Scripting (XSS) when using the SafeBuffer#bytesplice() function, the output of which is not treated as mutated and therefore improperly tagged as html_safe although it may contain executable scripts.

Workaround

Avoid calling bytesplice on a SafeBuffer (html_safe) string with untrusted user input.

Details

A cross-site scripting attack occurs when the attacker tricks a legitimate web-based application or site to accept a request as originating from a trusted source.

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 &lt; and > can be coded as &gt; 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 activesupport to version 6.1.7.3, 7.0.4.3 or higher.

References

Cross-site Scripting (XSS) vulnerability report

medium severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: activesupport
  • Introduced through: html-proofer@3.6.0 and jemoji@0.12.0

Detailed paths

  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › html-proofer@3.6.0 › activesupport@5.2.6
    Remediation: Upgrade to html-proofer@3.12.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jemoji@0.12.0 › html-pipeline@2.14.0 › activesupport@5.2.6
    Remediation: Upgrade to jemoji@0.12.0.

Overview

activesupport is a toolkit of support libraries and Ruby core extensions extracted from the Rails framework.

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS) in the underscore() function in inflector/methods.rb. This affects String#underscore, ActiveSupport::Inflector.underscore, String#titleize, and any other methods using these.

NOTE: The impact of this vulnerability may be mitigated by configuring Regexp.timeout. Additionally, patches have been released to address this issue: 6-1-Avoid-regex-backtracking-in-Inflector.underscore.patch, 7-0-Avoid-regex-backtracking-in-Inflector.underscore.patch

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 activesupport to version 6.1.7.1, 7.0.4.1 or higher.

References

Regular Expression Denial of Service (ReDoS) vulnerability report

medium severity

Denial of Service (DoS)

  • Vulnerable module: rexml
  • Introduced through: kramdown-parser-gfm@1.1.0, jekyll@4.0.1 and others

Detailed paths

  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to kramdown-parser-gfm@1.1.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll@4.0.1 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll@4.0.1.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll@4.0.1 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll@4.0.1.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-redirect-from@0.16.0 › jekyll@4.0.1 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-redirect-from@0.16.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-seo-tag@2.7.1 › jekyll@4.0.1 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-seo-tag@2.7.1.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-sitemap@1.4.0 › jekyll@4.0.1 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-sitemap@1.4.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jemoji@0.12.0 › jekyll@4.0.1 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jemoji@0.12.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-redirect-from@0.16.0 › jekyll@4.0.1 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-redirect-from@0.16.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-seo-tag@2.7.1 › jekyll@4.0.1 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-seo-tag@2.7.1.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-sitemap@1.4.0 › jekyll@4.0.1 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-sitemap@1.4.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jemoji@0.12.0 › jekyll@4.0.1 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jemoji@0.12.0.

…and 8 more

Overview

rexml is an An XML toolkit for Ruby.

Affected versions of this package are vulnerable to Denial of Service (DoS) through the XML parsing process. An attacker can cause a denial of service by sending specially crafted XML documents that contain many specific characters such as <, 0, and %>.

This vulnerability is exploitable if the application is configured to parse untrusted XML documents.

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 rexml to version 3.3.2 or higher.

References

Denial of Service (DoS) vulnerability report

medium severity

Uncontrolled Resource Consumption

  • Vulnerable module: rexml
  • Introduced through: kramdown-parser-gfm@1.1.0, jekyll@4.0.1 and others

Detailed paths

  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to kramdown-parser-gfm@1.1.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll@4.0.1 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll@4.0.1.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll@4.0.1 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll@4.0.1.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-redirect-from@0.16.0 › jekyll@4.0.1 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-redirect-from@0.16.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-seo-tag@2.7.1 › jekyll@4.0.1 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-seo-tag@2.7.1.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-sitemap@1.4.0 › jekyll@4.0.1 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-sitemap@1.4.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jemoji@0.12.0 › jekyll@4.0.1 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jemoji@0.12.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-redirect-from@0.16.0 › jekyll@4.0.1 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-redirect-from@0.16.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-seo-tag@2.7.1 › jekyll@4.0.1 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-seo-tag@2.7.1.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jekyll-sitemap@1.4.0 › jekyll@4.0.1 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jekyll-sitemap@1.4.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jemoji@0.12.0 › jekyll@4.0.1 › kramdown-parser-gfm@1.1.0 › kramdown@2.3.1 › rexml@3.2.5
    Remediation: Upgrade to jemoji@0.12.0.

…and 8 more

Overview

rexml is an An XML toolkit for Ruby.

Affected versions of this package are vulnerable to Uncontrolled Resource Consumption when parsing an XML that has many <s in an attribute value. An attacker can cause a denial of service by exploiting this behavior.

Workaround

This vulnerability can be mitigated by not parsing untrusted XMLs.

Remediation

Upgrade rexml to version 3.2.7 or higher.

References

Uncontrolled Resource Consumption vulnerability report

medium severity
new

Use After Free

  • Vulnerable module: nokogiri
  • Introduced through: nokogiri@1.11.4, html-proofer@3.6.0 and others

Detailed paths

  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › nokogiri@1.11.4
    Remediation: Upgrade to nokogiri@1.18.4.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › html-proofer@3.6.0 › nokogiri@1.11.4
    Remediation: Upgrade to html-proofer@3.6.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jemoji@0.12.0 › html-pipeline@2.14.0 › nokogiri@1.11.4
    Remediation: Upgrade to jemoji@0.12.0.

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to Use After Free through the numbers.c component. An attacker can cause memory corruption or execute arbitrary code by exploiting nested XPath evaluations where an XPath context node is modified but not restored.

Remediation

Upgrade nokogiri to version 1.18.4 or higher.

References

Use After Free vulnerability report

medium severity
new

Use After Free

  • Vulnerable module: nokogiri
  • Introduced through: nokogiri@1.11.4, html-proofer@3.6.0 and others

Detailed paths

  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › nokogiri@1.11.4
    Remediation: Upgrade to nokogiri@1.18.4.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › html-proofer@3.6.0 › nokogiri@1.11.4
    Remediation: Upgrade to html-proofer@3.6.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jemoji@0.12.0 › html-pipeline@2.14.0 › nokogiri@1.11.4
    Remediation: Upgrade to jemoji@0.12.0.

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to Use After Free through the xsltGetInheritedNsList process. An attacker can manipulate memory and potentially execute arbitrary code by excluding result prefixes.

Remediation

Upgrade nokogiri to version 1.18.4 or higher.

References

Use After Free vulnerability report

medium severity

Information Exposure

  • Vulnerable module: activesupport
  • Introduced through: html-proofer@3.6.0 and jemoji@0.12.0

Detailed paths

  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › html-proofer@3.6.0 › activesupport@5.2.6
    Remediation: Upgrade to html-proofer@3.12.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jemoji@0.12.0 › html-pipeline@2.14.0 › activesupport@5.2.6
    Remediation: Upgrade to jemoji@0.12.0.

Overview

activesupport is a toolkit of support libraries and Ruby core extensions extracted from the Rails framework.

Affected versions of this package are vulnerable to Information Exposure. The ImpactActiveSupport::EncryptedFile method writes contents that will be encrypted to a temporary file. The temporary file’s permissions are defaulted to the user’s current umask settings, meaning that it’s possible for other users on the same system to read the contents of the temporary file.

Note:

Attackers that have access to the file system could possibly read the contents of this temporary file while a user is editing it.

Workaround

Users can set the umask to be more restrictive: ruby$ umask 0077

Remediation

Upgrade activesupport to version 6.1.7.5, 7.0.7.1 or higher.

References

Information Exposure vulnerability report

low severity

Cross-site Scripting (XSS)

  • Vulnerable module: nokogiri
  • Introduced through: nokogiri@1.11.4, html-proofer@3.6.0 and others

Detailed paths

  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › nokogiri@1.11.4
    Remediation: Upgrade to nokogiri@1.15.7.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › html-proofer@3.6.0 › nokogiri@1.11.4
    Remediation: Upgrade to html-proofer@3.6.0.
  • Introduced through: 18F/portfolios@18F/portfolios#bde3b284680a57bcf6de4fad4aba770933a5b2e6 › jemoji@0.12.0 › html-pipeline@2.14.0 › nokogiri@1.11.4
    Remediation: Upgrade to jemoji@0.12.0.

Overview

nokogiri is a gem for parsing HTML, XML, SAX, and Reader.

Affected versions of this package are vulnerable to Cross-site Scripting (XSS) due to the configuration of HTML5 sanitization and overridden sanitizer's allowed tags. An attacker can inject malicious content by exploiting the allowed tags settings to bypass sanitization controls. This is only exploitable if HTML5 sanitization is enabled and the application developer has overridden the sanitizer's allowed tags to include both 'math' and 'style' elements or both 'svg' and 'style' elements.

Details

A cross-site scripting attack occurs when the attacker tricks a legitimate web-based application or site to accept a request as originating from a trusted source.

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 &lt; and > can be coded as &gt; 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 nokogiri to version 1.15.7, 1.16.8 or higher.

References

Cross-site Scripting (XSS) vulnerability report