CVE-2025-66567: ruby-saml has a SAML authentication bypass due to namespace handling (parser differential)
Summary
Ruby-saml up to and including 1.12.4, there is an authentication bypass vulnerability because of an incomplete fix for CVE-2025-25292. 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. The vulnerability does not affect the version 1.18.0.
Impact That allows an attacker to be able to execute a Signature Wrapping attack and bypass the authentication
Other sources
The ruby-saml library is for implementing the client side of a SAML authorization. ruby-saml versions up to and including 1.12.4 contain an authentication bypass vulnerability due to an incomplete fix for CVE-2025-25292. ReXML and Nokogiri parse XML differently, generating entirely different document structures from the same input. This allows an attacker to execute a Signature Wrapping attack. This issue is fixed in version 1.18.0.
— MITRE
Affected Software
Remediation
Event History
Frequently Asked Questions
What is the severity of CVE-2025-66567?
CVE-2025-66567 has been classified with a high severity due to its potential for authentication bypass.
How do I fix CVE-2025-66567?
To fix CVE-2025-66567, upgrade ruby-saml to version 1.18.0 or later.
What is the impact of CVE-2025-66567?
CVE-2025-66567 can allow attackers to bypass authentication mechanisms when using certain XML parsing libraries.
Which versions of ruby-saml are affected by CVE-2025-66567?
CVE-2025-66567 affects ruby-saml versions up to and including 1.12.4.
Is CVE-2025-66567 related to any other vulnerabilities?
Yes, CVE-2025-66567 is an incomplete fix for the previously reported CVE-2025-25292.