# CVE-2026-45363: ruby-jwt: ruby-jwt is a Ruby implementation of the RFC 7519 OAuth JSON Web Token standard

CVE-2026-45363 is fixed in ruby-jwt on 1 platform, first by DEBIAN-CVE-2026-45363, released July 19, 2026. It is not reported as exploited. Patch Radar priority: Urgent.

- Web page: https://patchblox.com/security/cve/CVE-2026-45363
- Priority: Urgent
- CVSS: 9.1 (critical)
- EPSS: 0.0036
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jul 14, 2026

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | ruby-jwt Debian 12.15 (bookworm) | 2.5.0-1+deb12u1 | [DEBIAN-CVE-2026-45363](https://patchblox.com/security/data/fix/linux/debian-cve-2026-45363.md) | Jul 19, 2026 |
| Linux | ruby-jwt Debian 13.5 (trixie) | 2.7.1-1+deb13u1 | [DEBIAN-CVE-2026-45363](https://patchblox.com/security/data/fix/linux/debian-cve-2026-45363.md) | Jul 19, 2026 |
| Linux | ruby-jwt Debian 14 | 3.2.0-1 | [DEBIAN-CVE-2026-45363](https://patchblox.com/security/data/fix/linux/debian-cve-2026-45363.md) | Jul 19, 2026 |

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Data as of 2026-11-09T01:18:40Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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