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CVE-2026-45363 (GCVE-0-2026-45363)

Vulnerability from cvelistv5 – Published: 2026-07-14 21:32 – Updated: 2026-07-15 13:26
VLAI
Title
`jwt` (Ruby gem) - empty-key HMAC bypass
Summary
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.
Severity
9.1 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
SSVC
Exploitation: none Automatable: yes Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-07-15 13:24 UTC
CWE
  • CWE-287 - Improper Authentication
  • CWE-326 - Inadequate Encryption Strength
  • CWE-1391 - Use of Weak Credentials
Assigner
References
Impacted products
Vendor Product Version CPE status
jwt ruby-jwt Affected: < 2.10.3
Affected: >= 3.0.0, < 3.2.0
guessed Create a notification for this product.
Show details on NVD website
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