Critical 9.3Published Dec 8, 2025

CVE-2025-66567ruby-saml has a SAML authentication bypass due to namespace handling (parser differential)

Updated under an hour ago (Oct 26, 2026, 7:23 PM ET)

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It affects SAML-Toolkits ruby-saml and 1 other product. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for SAML-Toolkits ruby-saml

Exploited in the last 30 days

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: 9.3 CRITICAL (v4.0, CNA)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
Weakness (CWE): CWE-347
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Analyzed
Record last updated: Dec 9, 2025
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

SAML-Toolkits ruby-saml saml_toolkits:ruby_saml (from the name)	before 1.18.0	CNA record
onelogin ruby-saml onelogin:ruby-saml	before 1.18.0	NVD

References

References

https://github.com/SAML-Toolkits/ruby-saml/security/advisories/GHSA-9v8j-x534-2fx3	x-refsource-confirm, vendor-advisory
https://github.com/SAML-Toolkits/ruby-saml/commit/e9c1cdbd0f9afa467b585de279db0cbd0fb8ae97	x-refsource-misc, patch
https://github.com/advisories/GHSA-754f-8gm6-c4r2	x-refsource-misc, not-applicable

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.