CVE-2025-66567criticalCWE-347

CVE-2025-66567: critical vulnerability in SAML-Toolkits ruby-saml

ruby-saml has a SAML authentication bypass due to namespace handling (parser differential)

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28Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 9.3epss 0.4%
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.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
Affected products
SAML-Toolkits · ruby-saml
Related CVEs — SAML-Toolkits ruby-saml

In the same product, most dangerous first.

CVE-2025-25292CRITICALRuby SAML vulnerable to SAML authentication bypass due to namespace handling (parser differential)EPSS 65.1%CVE-2025-25291CRITICALruby-saml vulnerable to SAML authentication bypass due to DOCTYPE handling (parser differential)EPSS 21.0%CVE-2024-45409CRITICALThe Ruby SAML library vulnerable to a SAML authentication bypass via Incorrect XPath selectorEPSS 12.5%CVE-2025-25293HIGHruby-saml vulnerable to Remote Denial of Service (DoS) with compressed SAML responsesEPSS 1.5%CVE-2025-54572MEDIUMRuby SAML DOS vulnerability with large SAML responseEPSS 0.5%CVE-2025-66568CRITICALruby-saml Libxml2 Canonicalization errors can bypass Digest/Signature validationEPSS 0.3%