CVE-2026-45363
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…
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.24%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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
- 9.1 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
- EPSS
- 0.24% probability · 15th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-287, CWE-326, CWE-1391
- Source
- security-advisories@github.com
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
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.