{"cve":"CVE-2026-107723","nvd":{"published":"2026-10-08T22:17:28.623","modified":"2026-10-14T02:16:57.877","status":"Deferred","description":"fast-jwt provides fast JSON Web Token (JWT) implementation. Prior to 6.3.0, fast-jwt createVerifier accepts a validly signed JWT whose payload is a JSON array because src/decoder.js checks that the payload is an object but does not reject arrays. The claim validator loop then finds no named exp, nbf, iss, aud, sub, jti, or nonce properties and silently skips those configured checks, returning the array as a successfully verified payload. An attacker who can produce or influence a validly signed token may bypass expiry, issuer, audience, subject, revocation, and replay protections. The opt-in requiredClaims option can block missing claims, and signature verification itself is not bypassed. This issue is fixed in version 6.3.0.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N","score":8.1},"cwes":["CWE-1287"],"references":["https://github.com/nearform/fast-jwt/commit/86e83efd8b5244f50859532d99244f0a9a9a4368","https://github.com/nearform/fast-jwt/pull/639","https://github.com/nearform/fast-jwt/releases/tag/v6.3.0","https://github.com/nearform/fast-jwt/security/advisories/GHSA-5hjw-83fp-phq9","https://github.com/nearform/fast-jwt/security/advisories/GHSA-5hjw-83fp-phq9"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:58:01.639778232+00:00"},"epss":{"cve":"CVE-2026-107723","score":0.00455,"percentile":0.39219,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-5hjw-83fp-phq9","url":"https://osv.dev/vulnerability/GHSA-5hjw-83fp-phq9","summary":"fast-jwt : Silent claim-validator bypass when JWT payload is a JSON array","modified":"2026-10-08T22:15:05.904211357Z","packages":[{"ecosystem":"npm","name":"fast-jwt","purl":"pkg:npm/fast-jwt","ranges":["<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."]}