GHSA-WX95-C6CV-8532

Nokogiri's CRuby extension fails to check the return value from xmlC14NExecute in the method Nokogiri::XML::Document#canonicalize and Nokogiri::XML::Node#canonicalize. When canonicalization fails, an empty string is returned instead of raising an exception. This incorrect return value may allow downstream libraries to accept invalid or incomplete canonicalized XML, which has been demonstrated to enable signature validation bypass in SAML libraries.

JRuby is not affected, as the Java implementation correctly raises RuntimeError on canonicalization failure.

Mitigation

Upgrade to Nokogiri >= 1.19.1.

Severity

The maintainers have assessed this as Medium severity. Nokogiri itself is a parsing library without a clear security boundary related to canonicalization, so the direct impact is that a method returns incorrect data on invalid input. However, this behavior was exploited in practice to bypass SAML signature validation in downstream libraries (see References).

Credit

This vulnerability was responsibly reported by HackerOne researcher d4d.

GHSA-WX95-C6CV-8532 has a CVSS score of 5.3 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.19.1); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is GHSA-WX95-C6CV-8532? GHSA-WX95-C6CV-8532 is a medium-severity security vulnerability in nokogiri (rubygems), affecting versions >= 1.5.1, < 1.19.1. It is fixed in 1.19.1.
2. How severe is GHSA-WX95-C6CV-8532? GHSA-WX95-C6CV-8532 has a CVSS score of 5.3 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of nokogiri are affected by GHSA-WX95-C6CV-8532? nokogiri (rubygems) versions >= 1.5.1, < 1.19.1 is affected.
4. Is there a fix for GHSA-WX95-C6CV-8532? Yes. GHSA-WX95-C6CV-8532 is fixed in 1.19.1. Upgrade to this version or later.
5. Is GHSA-WX95-C6CV-8532 exploitable, and should I be worried? Whether GHSA-WX95-C6CV-8532 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether GHSA-WX95-C6CV-8532 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix GHSA-WX95-C6CV-8532? Upgrade nokogiri to 1.19.1 or later.