CVE-2026-34950

{
  "id": "CVE-2026-34950",
  "sourceIdentifier": "[email protected]",
  "published": "2026-04-06T16:16:38.017",
  "lastModified": "2026-10-26T21:10:00.170",
  "vulnStatus": "Analyzed",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "fast-jwt provides fast JSON Web Token (JWT) implementation. In 6.1.0 and earlier, the publicKeyPemMatcher regex in fast-jwt/src/crypto.js uses a ^ anchor that is defeated by any leading whitespace in the key string, re-enabling the exact same JWT algorithm confusion attack that CVE-2023-48223 patched."
    },
    {
      "lang": "es",
      "value": "fast-jwt proporciona una implementación rápida de JSON Web Token (JWT). En la versión 6.1.0 y anteriores, la expresión regular publicKeyPemMatcher en fast-jwt/src/crypto.js utiliza un anclaje ^ que es anulado por cualquier espacio en blanco inicial en la cadena de clave, reactivando el mismo ataque de confusión de algoritmo JWT que CVE-2023-48223 parcheó."
    }
  ],
  "affected": [
    {
      "source": "[email protected]",
      "affectedData": [
        {
          "vendor": "nearform",
          "product": "fast-jwt",
          "versions": [
            {
              "version": "<= 6.1.0",
              "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:H/I:H/A:N",
          "baseScore": 9.1,
          "baseSeverity": "CRITICAL",
          "attackVector": "NETWORK",
          "attackComplexity": "LOW",
          "privilegesRequired": "NONE",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "availabilityImpact": "NONE"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 5.2
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-04-06T18:43:07.105733Z",
          "id": "CVE-2026-34950",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "weaknesses": [
    {
      "source": "[email protected]",
      "type": "Secondary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-327"
        }
      ]
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "operator": "OR",
          "negate": false,
          "cpeMatch": [
            {
              "vulnerable": true,
              "criteria": "cpe:2.3:a:nearform:fast-jwt:*:*:*:*:*:node.js:*:*",
              "versionEndExcluding": "6.2.0",
              "matchCriteriaId": "FD2BA255-333A-4CF2-9B8E-C685DF7A11A9"
            }
          ]
        }
      ]
    }
  ],
  "references": [
    {
      "url": "https://github.com/nearform/fast-jwt/security/advisories/GHSA-mvf2-f6gm-w987",
      "source": "[email protected]",
      "tags": [
        "Exploit",
        "Vendor Advisory"
      ]
    }
  ]
}