{"cve":"CVE-2026-107724","nvd":{"published":"2026-10-08T22:17:28.800","modified":"2026-10-09T16:17:23.740","status":"Deferred","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.","cvss_v4":null,"cvss_v3":{"version":"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},"cwes":["CWE-347"],"references":["https://github.com/nearform/fast-jwt/commit/10f9591349199ed2ab9fa1748ce92cdca697f6cf","https://github.com/nearform/fast-jwt/pull/636","https://github.com/nearform/fast-jwt/releases/tag/v6.3.0","https://github.com/nearform/fast-jwt/security/advisories/GHSA-g3jj-5cmm-3hxx","https://github.com/nearform/fast-jwt/security/advisories/GHSA-g3jj-5cmm-3hxx"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:58:01.639778232+00:00"},"epss":{"cve":"CVE-2026-107724","score":0.00282,"percentile":0.20465,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-g3jj-5cmm-3hxx","url":"https://osv.dev/vulnerability/GHSA-g3jj-5cmm-3hxx","summary":"fast-jwt treats raw public JWK JSON as an HMAC secret, enabling HS256 token forgery","modified":"2026-10-08T22:15:05.443432335Z","packages":[{"ecosystem":"npm","name":"fast-jwt","purl":"pkg:npm/fast-jwt","ranges":[">=6.2.4 <6.3.0"],"fixed":["6.3.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}