{"id":"CVE-2026-107724","revision":"452b795f1646422585ee8fd1acd86d69","records":[{"revision":"452b795f1646422585ee8fd1acd86d69","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-107724","aliases":[],"title":"fast-jwt treats raw public JWK JSON as an HMAC secret, enabling HS256 token forgery","description":"fast-jwt provides fast JSON Web Token (JWT) implementation. In 6.2.4, fast-jwt can classify raw serialized public JWK or JWKS JSON as an HMAC secret because src/crypto.js performDetectPublicKeyAlgorithms treats non-PEM strings as symmetric key material. If HS256 is explicitly allowed or inferred, an attacker who knows the exact serialized public-key bytes can use those bytes as an HMAC key and create a token containing arbitrary claims that createVerifier accepts. Serialization ordering or whitespace differences can prevent exploitation, and applications using supported PEM keys with an asymmetric-only algorithm allowlist are not affected. This issue is fixed in version 6.3.0.","state":0,"publishedAt":"2026-10-08T21:53:01.909+00:00","modifiedAt":"2026-10-09T15:51:27.488+00:00","affected":[{"ecosystem":"Vendor product","name":"fast-jwt","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"nearform\",\n                    \"product\": \"fast-jwt\",\n                    \"versions\": [\n                        {\n                            \"version\": \">= 6.2.4, < 6.3.0\",\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/nearform/fast-jwt/security/advisories/GHSA-g3jj-5cmm-3hxx","https://github.com/nearform/fast-jwt/pull/636","https://github.com/nearform/fast-jwt/commit/10f9591349199ed2ab9fa1748ce92cdca697f6cf","https://github.com/nearform/fast-jwt/releases/tag/v6.3.0"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-107724","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-107724","identifiers":["CVE-2026-107724"]},"retained":false,"historicalAffected":[]}],"coverage":[]}