{"id":"CVE-2026-102266","published":"2026-09-28T21:17:14.257","lastModified":"2026-09-29T20:17:12.053","description":"PyJWT is a Python implementation of JSON Web Token standards. From 2.13.0 until 2.14.0, HMACAlgorithm.from_jwk is affected because PyJWK verification path used the decoded key without applying prepare_key validation. This occurs when a trusted JWK Set contains an oct entry with an empty k value. As a result, an attacker signs an HMAC token with the same zero-length key accepted by PyJWT. Consequently, forged token can carry arbitrary authenticated claims. This issue is fixed in version 2.14.0.","cvssScore":7.4,"cvssSeverity":"HIGH","cvssVector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N","cwes":["CWE-347"],"vendors":[],"products":[],"references":[{"url":"https://github.com/jpadilla/pyjwt/commit/f91ed44dd65baaf457f4b3353ed35e98a753934c","tags":[]},{"url":"https://github.com/jpadilla/pyjwt/releases/tag/2.14.0","tags":[]},{"url":"https://github.com/jpadilla/pyjwt/security/advisories/GHSA-9j54-fg26-wv3r","tags":[]},{"url":"https://github.com/jpadilla/pyjwt/security/advisories/GHSA-9j54-fg26-wv3r","tags":[]}],"exploitRefs":[{"url":"https://github.com/jpadilla/pyjwt/commit/f91ed44dd65baaf457f4b3353ed35e98a753934c","tags":[]},{"url":"https://github.com/jpadilla/pyjwt/releases/tag/2.14.0","tags":[]},{"url":"https://github.com/jpadilla/pyjwt/security/advisories/GHSA-9j54-fg26-wv3r","tags":[]},{"url":"https://github.com/jpadilla/pyjwt/security/advisories/GHSA-9j54-fg26-wv3r","tags":[]}],"hasPoc":true,"ai":null}