{"id":"CVE-2026-102266","revision":"8551a4ddb99347c19a3c5a25b748f0dc","records":[{"revision":"8551a4ddb99347c19a3c5a25b748f0dc","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-102266","aliases":[],"title":"PyJWK accepts empty HMAC keys, bypassing PyJWT's empty-key validation","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.","state":0,"publishedAt":"2026-09-28T20:21:26.164+00:00","modifiedAt":"2026-09-29T19:35:42.049+00:00","affected":[{"ecosystem":"Vendor product","name":"pyjwt","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"jpadilla\",\n                    \"product\": \"pyjwt\",\n                    \"versions\": [\n                        {\n                            \"version\": \">= 2.13.0, < 2.14.0\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N","score":7.4,"severity":"HIGH"}],"references":["https://github.com/jpadilla/pyjwt/security/advisories/GHSA-9j54-fg26-wv3r","https://github.com/jpadilla/pyjwt/commit/f91ed44dd65baaf457f4b3353ed35e98a753934c","https://github.com/jpadilla/pyjwt/releases/tag/2.14.0"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-102266","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-102266","identifiers":["CVE-2026-102266"]},"retained":false,"historicalAffected":[]}],"coverage":[]}