{"id":"CVE-2026-102266","title":"PyJWT is a Python implementation of JSON Web Token standards","summary":"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 t…","severity":"high","cvss":7.4,"cvssVector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N","cwe":["CWE-347"],"vendor":"jpadilla","product":"pyjwt","affected":["pyjwt >= 2.13.0, < 2.14.0"],"published":"2026-09-28","updated":"2026-09-28","sourceUpdated":"2026-09-28T21:17:14.257","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-102266","references":[{"url":"https://github.com/jpadilla/pyjwt/commit/f91ed44dd65baaf457f4b3353ed35e98a753934c","label":"security-advisories@github.com"},{"url":"https://github.com/jpadilla/pyjwt/releases/tag/2.14.0","label":"security-advisories@github.com"},{"url":"https://github.com/jpadilla/pyjwt/security/advisories/GHSA-9j54-fg26-wv3r","label":"security-advisories@github.com"}],"tags":["nvd","cve.org"],"ingestedAt":"2026-09-28T21:20:54.779Z","slug":"CVE-2026-102266","body":"## Overview\n\nPyJWT 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":40.7,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}