CVE-2025-66568: critical vulnerability in SAML-Toolkits ruby-saml
ruby-saml Libxml2 Canonicalization errors can bypass Digest/Signature validation
Published
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28Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 9.3epss 0.3%
The ruby-saml library implements the client side of an SAML authorization. Versions up to and including 1.12.4, are vulnerable to authentication bypass through the libxml2 canonicalization process used by Nokogiri for document transformation, which allows an attacker to execute a Signature Wrapping attack. When libxml2’s canonicalization is invoked on an invalid XML input, it may return an empty string rather than a canonicalized node. ruby-saml then proceeds to compute the DigestValue over this empty string, treating it as if canonicalization succeeded. 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-samlRelated 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-2025-66567CRITICALruby-saml has a SAML authentication bypass due to namespace handling (parser differential)EPSS 0.4%