CVE-2026-35040

{
  "id": "CVE-2026-35040",
  "sourceIdentifier": "[email protected]",
  "published": "2026-04-09T16:16:27.213",
  "lastModified": "2026-10-26T21:10:00.170",
  "vulnStatus": "Analyzed",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "fast-jwt provides fast JSON Web Token (JWT) implementation. Prior to 6.2.1, using certain modifiers on RegExp objects in the allowedAud, allowedIss, allowedSub, allowedJti, or allowedNonce options in verify functions can cause certain unintended behaviours. This is because some modifiers are stateful and will cause failures in every second verification attempt regardless of the validity of the token provided. Such modifiers are /g (global matching) and /y (sticky matching). This does NOT allow invalid tokens to be accepted, only for valid tokens to be improperly rejected in some configurations. Instead it causes 50% of valid authentication requests to fail in an alternating pattern. This vulnerability is fixed in 6.2.1."
    },
    {
      "lang": "es",
      "value": "fast-jwt proporciona una implementación rápida de JSON Web Token (JWT). Antes de la versión 6.2.1, el uso de ciertos modificadores en objetos RegExp en las opciones allowedAud, allowedIss, allowedSub, allowedJti o allowedNonce en las funciones de verificación puede causar ciertos comportamientos no deseados. Esto se debe a que algunos modificadores tienen estado y causarán fallos en cada segundo intento de verificación, independientemente de la validez del token proporcionado. Dichos modificadores son /g (coincidencia global) y /y (coincidencia persistente). Esto NO permite que se acepten tokens inválidos, solo que los tokens válidos sean rechazados incorrectamente en algunas configuraciones. En su lugar, causa que el 50% de las solicitudes de autenticación válidas fallen en un patrón alterno. Esta vulnerabilidad está corregida en la versión 6.2.1."
    }
  ],
  "affected": [
    {
      "source": "[email protected]",
      "affectedData": [
        {
          "vendor": "nearform",
          "product": "fast-jwt",
          "versions": [
            {
              "version": "< 6.2.1",
              "status": "affected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV31": [
      {
        "source": "[email protected]",
        "type": "Secondary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
          "baseScore": 5.3,
          "baseSeverity": "MEDIUM",
          "attackVector": "NETWORK",
          "attackComplexity": "LOW",
          "privilegesRequired": "NONE",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "availabilityImpact": "LOW"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 1.4
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-04-13T20:03:24.317971Z",
          "id": "CVE-2026-35040",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "weaknesses": [
    {
      "source": "[email protected]",
      "type": "Secondary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-440"
        },
        {
          "lang": "en",
          "value": "CWE-697"
        }
      ]
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "operator": "OR",
          "negate": false,
          "cpeMatch": [
            {
              "vulnerable": true,
              "criteria": "cpe:2.3:a:nearform:fast-jwt:*:*:*:*:*:node.js:*:*",
              "versionEndExcluding": "6.2.1",
              "matchCriteriaId": "2B44A0FB-C037-42E0-9666-7491FF59219D"
            }
          ]
        }
      ]
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  ],
  "references": [
    {
      "url": "https://github.com/nearform/fast-jwt/commit/18d25904e4617e8753526d1b3ab5a2cccdea726a",
      "source": "[email protected]",
      "tags": [
        "Patch"
      ]
    },
    {
      "url": "https://github.com/nearform/fast-jwt/pull/593",
      "source": "[email protected]",
      "tags": [
        "Issue Tracking",
        "Patch"
      ]
    },
    {
      "url": "https://github.com/nearform/fast-jwt/releases/tag/v6.2.1",
      "source": "[email protected]",
      "tags": [
        "Product",
        "Release Notes"
      ]
    },
    {
      "url": "https://github.com/nearform/fast-jwt/security/advisories/GHSA-3j8v-cgw4-2g6q",
      "source": "[email protected]",
      "tags": [
        "Exploit",
        "Mitigation",
        "Vendor Advisory"
      ]
    }
  ]
}