Ruby SAML allows a SAML authentication bypass due to DOCTYPE handling (parser differential)
Published: March 12, 2025
SECURITY IDENTIFIERS
- CVE: CVE-2025-25291 (NVD)
- GHSA: GHSA-4vc4-m8qh-g8jm
- Vendor Advisory: https://github.com/SAML-Toolkits/ruby-saml/security/advisories/GHSA-4vc4-m8qh-g8jm
GEM
SEVERITY
CVSS v3.x: 9.8 (Critical)
PATCHED VERSIONS
~> 1.12.4
>= 1.18.0
DESCRIPTION
Summary
An authentication bypass vulnerability was found in ruby-saml due to a parser differential. ReXML and Nokogiri parse XML differently, the parsers can generate entirely different document structures from the same XML input. That allows an attacker to be able to execute a Signature Wrapping attack.
Impact
This issue may lead to authentication bypass.
RELATED
- https://github.com/SAML-Toolkits/ruby-saml/security/advisories/GHSA-4vc4-m8qh-g8jm
- https://github.com/SAML-Toolkits/ruby-saml/commit/e9c1cdbd0f9afa467b585de279db0cbd0fb8ae97
- https://github.com/omniauth/omniauth-saml/security/advisories/GHSA-hw46-3hmr-x9xv
- https://nvd.nist.gov/vuln/detail/CVE-2025-25291
- https://github.com/SAML-Toolkits/ruby-saml/commit/e76c5b36bac40aedbf1ba7ffaaf495be63328cd9
- https://about.gitlab.com/releases/2025/03/12/patch-release-gitlab-17-9-2-released
- https://github.blog/security/sign-in-as-anyone-bypassing-saml-sso-authentication-with-parser-differentials
- https://github.com/SAML-Toolkits/ruby-saml/releases/tag/v1.12.4
- https://github.com/SAML-Toolkits/ruby-saml/releases/tag/v1.18.0
- https://github.com/advisories/GHSA-4vc4-m8qh-g8jm