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VulnerabilityPublished

CVE-2025-66567: ruby-saml · Improper Verification of Cryptographic Signature

Affects ruby-samlSource CVE Database V5

0

Mentioned vulnerabilities

Not known to be exploited · CVSS 9.3 Critical : upgrade to 1.18.0 as a priority.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 4.0 base score
9.3Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.4% chance of exploitation in 30 days – higher than 35% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 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

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 9 Dec 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade ruby-saml to 1.18.0.

Affected software

ProductAffectedFixed in
RubyGemsruby-samlpkg:gem/ruby-samlOther threatsAffected
  • <1.18.0
Fixed in
  • 1.18.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

  1. Immediately upgrade all ruby-saml dependencies to version 1.18.0 or later, which contains the fix for this vulnerability.
  2. Conduct an inventory of all applications and services using ruby-saml to ensure no outdated versions remain in production or development environments.
  3. Review and harden XML parsing configurations to enforce consistent and secure parsing behavior, potentially restricting or validating XML inputs more strictly.
  4. Implement additional monitoring and anomaly detection for SAML authentication flows to detect unusual or unauthorized access attempts.
  5. Consider deploying Web Application Firewalls (WAFs) with rules to detect and block XML Signature Wrapping attack patterns.
  6. Educate development teams about secure XML handling and the risks of signature wrapping attacks to prevent similar issues in future code.
  7. Perform penetration testing and code audits focusing on SAML authentication components to identify residual weaknesses.
  8. Coordinate with identity providers and service providers to ensure end-to-end security of SAML assertions and tokens.

Description

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.

References

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