CVE-2026-45363`jwt` (Ruby gem) - empty-key HMAC bypass
- 9.1CriticalCVSS base score
- 0.36%Exploitation in 30 daysEPSS · top 69% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
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.
Timeline
ID reserved
By GitHub_M
- 2 months later
· 2 months later
Published
- 2 months later
· 2 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 3.1 | Critical9.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N |
| NVDNVD · Deferred | 3.1 | Critical9.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N |
- EPSS (exploitation in 30 days)
- 0.36% · top 69% of all CVEs (13 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: yes · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: Critical 9.1.
Affected products
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- RubyGemsjwtGHSA-c32j-vqhx-rx3x (opens in a new tab)
References
References6
- https://github.com/jwt/ruby-jwt/security/advisories/GHSA-c32j-vqhx-rx3x (opens in a new tab)x_refsource_CONFIRM
- https://github.com/jwt/ruby-jwt/commit/9820020869ad147b941e49d96ab8beba35532964 (opens in a new tab)x_refsource_MISC
- https://github.com/jwt/ruby-jwt/commit/db560b769a07bd9724e77ff505011ac01872106f (opens in a new tab)x_refsource_MISC
- https://github.com/jwt/ruby-jwt/releases/tag/v2.10.3 (opens in a new tab)x_refsource_MISC
- https://github.com/jwt/ruby-jwt/releases/tag/v3.2.0 (opens in a new tab)x_refsource_MISC
- https://lists.debian.org/debian-lts-announce/2026/09/msg00022.html (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-44516 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-c32j-vqhx-rx3x (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-45363)Record last updated .