{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "6.2.4"
              },
              {
                "fixed": "6.3.0"
              }
            ],
            "source": "AFFECTED_FIELD"
          },
          "events": [
            {
              "introduced": "044bf42c8e0a2eda8afc0819f97ae435c4214e3c"
            },
            {
              "fixed": "b351e31a755cdce457e0d25ce22b139bbcf469da"
            }
          ],
          "repo": "https://github.com/nearform/fast-jwt",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-g3jj-5cmm-3hxx"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-347"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/107xxx/CVE-2026-107724.json"
  },
  "details": "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.",
  "id": "CVE-2026-107724",
  "modified": "2026-10-09T10:31:15.424318184Z",
  "published": "2026-10-08T21:53:01.909Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/107xxx/CVE-2026-107724.json"
    },
    {
      "type": "FIX",
      "url": "https://github.com/nearform/fast-jwt/commit/10f9591349199ed2ab9fa1748ce92cdca697f6cf"
    },
    {
      "type": "FIX",
      "url": "https://github.com/nearform/fast-jwt/pull/636"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nearform/fast-jwt/releases/tag/v6.3.0"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/nearform/fast-jwt/security/advisories/GHSA-g3jj-5cmm-3hxx"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-107724"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "fast-jwt treats raw public JWK JSON as an HMAC secret, enabling HS256 token forgery"
}