CVE-2026-45363

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.

• github.comhttps://github.com/jwt/ruby-jwt/commit/9820020869ad147b941e49d96ab8beba35532964
• github.comhttps://github.com/jwt/ruby-jwt/commit/db560b769a07bd9724e77ff505011ac01872106f
• github.comhttps://github.com/jwt/ruby-jwt/releases/tag/v2.10.3
• github.comhttps://github.com/jwt/ruby-jwt/releases/tag/v3.2.0
• github.comhttps://github.com/jwt/ruby-jwt/security/advisories/GHSA-c32j-vqhx-rx3x