CVE-2026-45363

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 3.1 breakdown

Remediation

No fixed version is recorded in the NVD data. Check the vendor advisory for the latest guidance.

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
• https://lists.debian.org/debian-lts-announce/2026/09/msg00022.html

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