CVE-2025-66567: ruby-saml · Improper Verification of Cryptographic Signature
Affects ruby-samlSource CVE Database V5
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, 14:05 UTC
- 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:NExploitation evidence
Disclosed: evidence found.
CVE published 9 Dec 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
| Product | Affected | Fixed in |
|---|---|---|
RubyGemsruby-samlpkg:gem/ruby-samlOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
- Immediately upgrade all ruby-saml dependencies to version 1.18.0 or later, which contains the fix for this vulnerability.
- Conduct an inventory of all applications and services using ruby-saml to ensure no outdated versions remain in production or development environments.
- Review and harden XML parsing configurations to enforce consistent and secure parsing behavior, potentially restricting or validating XML inputs more strictly.
- Implement additional monitoring and anomaly detection for SAML authentication flows to detect unusual or unauthorized access attempts.
- Consider deploying Web Application Firewalls (WAFs) with rules to detect and block XML Signature Wrapping attack patterns.
- Educate development teams about secure XML handling and the risks of signature wrapping attacks to prevent similar issues in future code.
- Perform penetration testing and code audits focusing on SAML authentication components to identify residual weaknesses.
- 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.