CVE-2025-25291: ruby-saml vulnerable to SAML authentication bypass due to DOCTYPE handling (parser differential)
First published: Wed Mar 12 2025(Updated: )
### 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.
Credit: security-advisories@github.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| ruby-saml | <1.12.4<1.18.0 | |
| rubygems/ruby-saml | >=1.13.0<1.18.0 | 1.18.0 |
| rubygems/ruby-saml | <1.12.4 | 1.12.4 |
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Reference Links
- https://github.com/SAML-Toolkits/ruby-saml/security/advisories/GHSA-4vc4-m8qh-g8jm
- https://github.com/omniauth/omniauth-saml/security/advisories/GHSA-hw46-3hmr-x9xv
- https://github.com/SAML-Toolkits/ruby-saml/commit/e76c5b36bac40aedbf1ba7ffaaf495be63328cd9
- https://github.com/SAML-Toolkits/ruby-saml/commit/e9c1cdbd0f9afa467b585de279db0cbd0fb8ae97
- 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://about.gitlab.com/releases/2025/03/12/patch-release-gitlab-17-9-2-released
- https://nvd.nist.gov/vuln/detail/CVE-2025-25291
- https://github.blog/security/sign-in-as-anyone-bypassing-saml-sso-authentication-with-parser-differentials
- https://github.com/advisories/GHSA-4vc4-m8qh-g8jm (Advisory)
Frequently Asked Questions
What is the severity of CVE-2025-25291?
The severity of CVE-2025-25291 is high due to the potential for authentication bypass.
How do I fix CVE-2025-25291?
To fix CVE-2025-25291, upgrade ruby-saml to versions 1.12.4 or 1.18.0 or later.
What product is affected by CVE-2025-25291?
CVE-2025-25291 affects the ruby-saml library.
What versions of ruby-saml are impacted by CVE-2025-25291?
ruby-saml versions prior to 1.12.4 and between 1.13.0 and 1.18.0 are impacted by CVE-2025-25291.
How does CVE-2025-25291 exploit a parser differential?
CVE-2025-25291 exploits the difference in XML parsing between ReXML and Nokogiri, leading to different document structures.
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