CVE-2026-33808

{
  "id": "CVE-2026-33808",
  "sourceIdentifier": "ce714d77-add3-4f53-aff5-83d477b104bb",
  "published": "2026-04-15T10:16:48.453",
  "lastModified": "2026-10-26T22:10:00.163",
  "vulnStatus": "Analyzed",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Impact@fastify/express v4.0.4 and earlier fails to normalize URLs before passing them to Express middleware when Fastify router normalization options are enabled. This allows complete bypass of path-scoped authentication middleware via duplicate slashes when ignoreDuplicateSlashes is enabled, or via semicolon delimiters when useSemicolonDelimiter is enabled. In both cases, Fastify router normalizes the URL and matches the route, but @fastify/express passes the original un-normalized URL to Express middleware, which fails to match and is skipped. An unauthenticated attacker can access protected routes by manipulating the URL path.\n\nPatchesUpgrade to @fastify/express v4.0.5 or later."
    },
    {
      "lang": "es",
      "value": "Impacto: @fastify/express v4.0.4 y anteriores no normaliza las URL antes de pasarlas al middleware de Express cuando las opciones de normalización del router de Fastify están habilitadas. Esto permite una omisión completa del middleware de autenticación con ámbito de ruta a través de barras duplicadas cuando ignoreDuplicateSlashes está habilitado, o a través de delimitadores de punto y coma cuando useSemicolonDelimiter está habilitado. En ambos casos, el router de Fastify normaliza la URL y coincide con la ruta, pero @fastify/express pasa la URL original no normalizada al middleware de Express, que no coincide y es omitido. Un atacante no autenticado puede acceder a rutas protegidas manipulando la ruta de la URL.\n\nParches: Actualice a @fastify/express v4.0.5 o posterior."
    }
  ],
  "affected": [
    {
      "source": "ce714d77-add3-4f53-aff5-83d477b104bb",
      "affectedData": [
        {
          "vendor": "fastify",
          "product": "@fastify/express",
          "defaultStatus": "unaffected",
          "packageURL": "pkg:npm/@fastify/express",
          "versions": [
            {
              "version": "0",
              "lessThan": "4.0.5",
              "versionType": "semver",
              "status": "affected"
            },
            {
              "version": "4.0.5",
              "versionType": "semver",
              "status": "unaffected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV40": [
      {
        "source": "ce714d77-add3-4f53-aff5-83d477b104bb",
        "type": "Secondary",
        "cvssData": {
          "version": "4.0",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
          "baseScore": 9.1,
          "baseSeverity": "CRITICAL",
          "attackVector": "NETWORK",
          "attackComplexity": "LOW",
          "attackRequirements": "PRESENT",
          "privilegesRequired": "NONE",
          "userInteraction": "NONE",
          "vulnConfidentialityImpact": "HIGH",
          "vulnIntegrityImpact": "HIGH",
          "vulnAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "NONE",
          "subAvailabilityImpact": "NONE",
          "exploitMaturity": "NOT_DEFINED",
          "confidentialityRequirement": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "availabilityRequirement": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "valueDensity": "NOT_DEFINED",
          "vulnerabilityResponseEffort": "NOT_DEFINED",
          "providerUrgency": "NOT_DEFINED"
        }
      }
    ],
    "cvssMetricV31": [
      {
        "source": "[email protected]",
        "type": "Primary",
        "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": "2026-04-15T13:10:17.328470Z",
          "id": "CVE-2026-33808",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "weaknesses": [
    {
      "source": "ce714d77-add3-4f53-aff5-83d477b104bb",
      "type": "Secondary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-436"
        }
      ]
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "operator": "OR",
          "negate": false,
          "cpeMatch": [
            {
              "vulnerable": true,
              "criteria": "cpe:2.3:a:fastify:fastify\\/express:*:*:*:*:*:node.js:*:*",
              "versionEndExcluding": "4.0.5",
              "matchCriteriaId": "FD8C629A-73A6-46F2-BA53-823A9CE66738"
            }
          ]
        }
      ]
    }
  ],
  "references": [
    {
      "url": "https://cna.openjsf.org/security-advisories.html",
      "source": "ce714d77-add3-4f53-aff5-83d477b104bb",
      "tags": [
        "Vendor Advisory"
      ]
    },
    {
      "url": "https://github.com/fastify/fastify-express/security/advisories/GHSA-6hw5-45gm-fj88",
      "source": "ce714d77-add3-4f53-aff5-83d477b104bb",
      "tags": [
        "Exploit",
        "Mitigation",
        "Vendor Advisory"
      ]
    },
    {
      "url": "https://github.com/fastify/fastify-express/security/advisories/GHSA-6hw5-45gm-fj88",
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "tags": [
        "Exploit",
        "Mitigation",
        "Vendor Advisory"
      ]
    }
  ]
}