{"cve":"CVE-2025-30144","nvd":{"published":"2025-03-19T16:15:33.080","modified":"2026-06-17T09:08:14.723","status":"Deferred","description":"fast-jwt provides fast JSON Web Token (JWT) implementation. Prior to 5.0.6, the fast-jwt library does not properly validate the iss claim based on the RFC 7519. The iss (issuer) claim validation within the fast-jwt library permits an array of strings as a valid iss value. This design flaw enables a potential attack where a malicious actor crafts a JWT with an iss claim structured as ['https://attacker-domain/', 'https://valid-iss']. Due to the permissive validation, the JWT will be deemed valid. Furthermore, if the application relies on external libraries like get-jwks that do not independently validate the iss claim, the attacker can leverage this vulnerability to forge a JWT that will be accepted by the victim application. Essentially, the attacker can insert their own domain into the iss array, alongside the legitimate issuer, and bypass the intended security checks. This issue is fixed in 5.0.6.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N","score":6.5},"cwes":["CWE-290","CWE-345"],"references":["https://datatracker.ietf.org/doc/html/rfc7519#page-9","https://github.com/nearform/fast-jwt/commit/cc26b1d473f900446ad846f8f0b10eb1c0adcbdd","https://github.com/nearform/fast-jwt/security/advisories/GHSA-gm45-q3v2-6cf8"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:00:17.429720821+00:00"},"epss":{"cve":"CVE-2025-30144","score":0.00592,"percentile":0.48316,"date":"2026-11-01"},"kev":null,"osv":[{"id":"GHSA-gm45-q3v2-6cf8","url":"https://osv.dev/vulnerability/GHSA-gm45-q3v2-6cf8","summary":"Fast-JWT Improperly Validates iss Claims","modified":"2025-03-20T18:58:42Z","packages":[{"ecosystem":"npm","name":"fast-jwt","purl":"pkg:npm/fast-jwt","ranges":["<5.0.6"],"fixed":["5.0.6"]}]}],"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."]}