CVE-2025-25291: Ruby SAML allows a SAML authentication bypass due to DOCTYPE handling (parser differential)
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.
Published Mar 12, 2025 · Updated Nov 3, 2025
Affected packages
ruby-saml
- Ecosystem
- RubyGems
- Affected
- < 1.12.4
- Fixed in
- 1.12.4
- Check
bundle info ruby-saml
ruby-saml
- Ecosystem
- RubyGems
- Affected
- >= 1.13.0, < 1.18.0
- Fixed in
- 1.18.0
- Check
bundle info ruby-saml
Advisory details
From the GitHub Advisory Database (CC BY 4.0).
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.
Credited to ahacker1-securesaml.
References
- 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/rubysec/ruby-advisory-db/blob/master/gems/ruby-saml/CVE-2025-25291.yml
- https://security.netapp.com/advisory/ntap-20250314-0010
- https://news.ycombinator.com/item?id=43374519
- https://portswigger.net/research/saml-roulette-the-hacker-always-wins
- https://securitylab.github.com/advisories/GHSL-2024-329_GHSL-2024-330_ruby-saml
- https://lists.debian.org/debian-lts-announce/2025/04/msg00011.html
- https://github.com/advisories/GHSA-4vc4-m8qh-g8jm
How this page is made: the data panel comes from the GitHub Advisory Database, CISA’s KEV catalog, the NVD and FIRST EPSS, and updates twice a day. No analysis has been written for this entry yet. Methodology
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