`jwt` (Ruby gem) - empty-key HMAC bypass
Summary
| CVE | CVE-2026-45363 |
|---|---|
| State | PUBLISHED |
| Assigner | GitHub_M |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-07-14 22:16:54 UTC |
| Updated | 2026-07-14 22:16:54 UTC |
| 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. |
Risk And Classification
Primary CVSS: v3.1 9.1 CRITICAL from [email protected]
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Problem Types: CWE-287 | CWE-326 | CWE-1391 | CWE-287 CWE-287: Improper Authentication | CWE-326 CWE-326: Inadequate Encryption Strength | CWE-1391 CWE-1391: Use of Weak Credentials
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | [email protected] | Secondary | 9.1 | CRITICAL | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N |
| 3.1 | CNA | DECLARED | 9.1 | CRITICAL | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N |
CVSS v3.1 Breakdown
Attack Vector
NetworkAttack Complexity
LowPrivileges Required
NoneUser Interaction
NoneScope
UnchangedConfidentiality
HighIntegrity
HighAvailability
NoneCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Vendor Declared Affected Products
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/jwt/ruby-jwt/commit/db560b769a07bd9724e77ff505011ac01872106f | [email protected] | github.com | |
| github.com/jwt/ruby-jwt/security/advisories/GHSA-c32j-vqhx-rx3x | [email protected] | github.com | |
| github.com/jwt/ruby-jwt/releases/tag/v3.2.0 | [email protected] | github.com | |
| github.com/jwt/ruby-jwt/commit/9820020869ad147b941e49d96ab8beba35532964 | [email protected] | github.com | |
| github.com/jwt/ruby-jwt/releases/tag/v2.10.3 | [email protected] | github.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.