Vulnerability Description
ruby-jwt is a Ruby implementation of the RFC 7519 OAuth JSON Web Token standard. Prior to 2.10.3 and 3.2.0, JWT.decode(token, '', true, algorithm: 'HS256') accepts an attacker-forged token because OpenSSL::HMAC.digest('SHA256', '', payload) returns a valid digest under an empty key and no empty-key precondition exists in the HMAC algorithm. The same path is reached when a keyfinder block or key_finder: argument returns an empty string, nil, or an array containing nil for an unknown key, affecting HS256, HS384, and HS512 verification through JWT.decode and JWT::EncodedToken#verify_signature!. This issue is fixed in versions 2.10.3 and 3.2.0.
CVSS Score
CRITICAL
Related Weaknesses (CWE)
References
- https://github.com/jwt/ruby-jwt/commit/9820020869ad147b941e49d96ab8beba35532964
- https://github.com/jwt/ruby-jwt/commit/db560b769a07bd9724e77ff505011ac01872106f
- https://github.com/jwt/ruby-jwt/releases/tag/v2.10.3
- https://github.com/jwt/ruby-jwt/releases/tag/v3.2.0
- https://github.com/jwt/ruby-jwt/security/advisories/GHSA-c32j-vqhx-rx3x
FAQ
What is CVE-2026-45363?
CVE-2026-45363 is a vulnerability with a CVSS score of 9.1 (CRITICAL). ruby-jwt is a Ruby implementation of the RFC 7519 OAuth JSON Web Token standard. Prior to 2.10.3 and 3.2.0, JWT.decode(token, '', true, algorithm: 'HS256') accepts an attacker-forged token because Ope...
How severe is CVE-2026-45363?
CVE-2026-45363 has been rated CRITICAL with a CVSS base score of 9.1/10. This is considered a critical vulnerability requiring immediate attention.
Is there a patch for CVE-2026-45363?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.