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CVE-2026-45363

`jwt` (Ruby gem) - empty-key HMAC bypass PUBLISHED

Description (CNA)

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.

Affected (CNA)

Vendor / productVersions
jwt / ruby-jwtaffected < 2.10.3; affected >= 3.0.0, < 3.2.0

CWE

CWE-287, CWE-326, CWE-1391

References

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.

CVE

No English description supplied.