Search criteria ⓘ Use this form to refine search results.
Full-text search supports keyword queries with ranking and filtering.
You can combine vendor, product, and sources to narrow results.
Enable “Apply ordering” to sort by date instead of relevance.

4 vulnerabilities found for @fastify/express by fastify

CVE-2026-33808 (GCVE-0-2026-33808)

Vulnerability from nvd – Published: 2026-04-15 09:29 – Updated: 2026-04-15 13:10
VLAI?
Title
@fastify/express vulnerable to middleware authentication bypass via URL normalization gaps (duplicate slashes and semicolons)
Summary
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. PatchesUpgrade to @fastify/express v4.0.5 or later.
Severity ?
9.1 (Critical)
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
CWE
  • CWE-436 - Interpretation Conflict
Assigner
References
Impacted products
Vendor Product Version
fastify @fastify/express Affected: 0 , < 4.0.5 (semver)
Unaffected: 4.0.5 (semver)
Create a notification for this product.
Credits
FredKSchott mcollina UlisesGascon climba03003
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-33808",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-04-15T13:10:17.328470Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-04-15T13:10:24.054Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/fastify/fastify-express/security/advisories/GHSA-6hw5-45gm-fj88"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "packageURL": "pkg:npm/@fastify/express",
          "product": "@fastify/express",
          "vendor": "fastify",
          "versions": [
            {
              "lessThan": "4.0.5",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "4.0.5",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "reporter",
          "value": "FredKSchott"
        },
        {
          "lang": "en",
          "type": "remediation developer",
          "value": "mcollina"
        },
        {
          "lang": "en",
          "type": "remediation reviewer",
          "value": "UlisesGascon"
        },
        {
          "lang": "en",
          "type": "remediation reviewer",
          "value": "climba03003"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003ch3\u003eImpact\u003c/h3\u003e@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.\u003cbr\u003e\u003cbr\u003e\u003ch3\u003ePatches\u003c/h3\u003eUpgrade to @fastify/express v4.0.5 or later."
            }
          ],
          "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."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 9.1,
            "baseSeverity": "CRITICAL",
            "exploitMaturity": "NOT_DEFINED",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
            "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",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "HIGH",
            "vulnIntegrityImpact": "HIGH",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-436",
              "description": "CWE-436: Interpretation Conflict",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-04-15T09:29:46.091Z",
        "orgId": "ce714d77-add3-4f53-aff5-83d477b104bb",
        "shortName": "openjs"
      },
      "references": [
        {
          "url": "https://github.com/fastify/fastify-express/security/advisories/GHSA-6hw5-45gm-fj88"
        },
        {
          "url": "https://cna.openjsf.org/security-advisories.html"
        }
      ],
      "title": "@fastify/express vulnerable to middleware authentication bypass via URL normalization gaps (duplicate slashes and semicolons)",
      "x_generator": {
        "engine": "cve-kit 1.0.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "ce714d77-add3-4f53-aff5-83d477b104bb",
    "assignerShortName": "openjs",
    "cveId": "CVE-2026-33808",
    "datePublished": "2026-04-15T09:29:46.091Z",
    "dateReserved": "2026-03-23T19:48:48.715Z",
    "dateUpdated": "2026-04-15T13:10:24.054Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

CVE-2026-33807 (GCVE-0-2026-33807)

Vulnerability from nvd – Published: 2026-04-15 09:52 – Updated: 2026-04-15 13:09
VLAI?
Title
@fastify/express vulnerable to middleware path doubling causing authentication bypass in child plugin scopes
Summary
@fastify/express v4.0.4 and earlier contains a path handling bug in the onRegister function that causes middleware paths to be doubled when inherited by child plugins. When a child plugin is registered with a prefix that matches a middleware path, the middleware path is prefixed a second time, causing it to never match incoming requests. This results in complete bypass of Express middleware security controls, including authentication, authorization, and rate limiting, for all routes defined within affected child plugin scopes. No special configuration or request crafting is required. Upgrade to @fastify/express v4.0.5 or later.
Severity ?
9.1 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CWE
  • CWE-436 - Interpretation Conflict
Assigner
References
Impacted products
Vendor Product Version
fastify @fastify/express Affected: 0 , < 4.0.5 (semver)
Unaffected: 4.0.5 (semver)
Create a notification for this product.
Credits
FredKSchott mcollina UlisesGascon climba03003
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-33807",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-04-15T13:09:41.621709Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-04-15T13:09:45.259Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/fastify/fastify-express/security/advisories/GHSA-hrwm-hgmj-7p9c"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "packageURL": "pkg:npm/@fastify/express",
          "product": "@fastify/express",
          "vendor": "fastify",
          "versions": [
            {
              "lessThan": "4.0.5",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "4.0.5",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "reporter",
          "value": "FredKSchott"
        },
        {
          "lang": "en",
          "type": "remediation developer",
          "value": "mcollina"
        },
        {
          "lang": "en",
          "type": "remediation reviewer",
          "value": "UlisesGascon"
        },
        {
          "lang": "en",
          "type": "remediation reviewer",
          "value": "climba03003"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003ch3\u003e\u003cspan\u003e\u003cspan\u003e@fastify/express v4.0.4 and earlier contains a path handling bug in the onRegister function that causes middleware paths to be doubled when inherited by child plugins. When a child plugin is registered with a prefix that matches a middleware path, the middleware path is prefixed a second time, causing it to never match incoming requests. This results in complete bypass of Express middleware security controls, including authentication, authorization, and rate limiting, for all routes defined within affected child plugin scopes. No special configuration or request crafting is required.\u003cbr\u003e\u003c/span\u003e\u003cspan\u003e\u003cbr\u003eUpgrade to @fastify/express v4.0.5 or later.\u003c/span\u003e\u003c/span\u003e\u003c/h3\u003e"
            }
          ],
          "value": "@fastify/express v4.0.4 and earlier contains a path handling bug in the onRegister function that causes middleware paths to be doubled when inherited by child plugins. When a child plugin is registered with a prefix that matches a middleware path, the middleware path is prefixed a second time, causing it to never match incoming requests. This results in complete bypass of Express middleware security controls, including authentication, authorization, and rate limiting, for all routes defined within affected child plugin scopes. No special configuration or request crafting is required.\n\nUpgrade to @fastify/express v4.0.5 or later."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 9.1,
            "baseSeverity": "CRITICAL",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N",
            "version": "3.1"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-436",
              "description": "CWE-436: Interpretation Conflict",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-04-15T09:55:50.627Z",
        "orgId": "ce714d77-add3-4f53-aff5-83d477b104bb",
        "shortName": "openjs"
      },
      "references": [
        {
          "url": "https://github.com/fastify/fastify-express/security/advisories/GHSA-hrwm-hgmj-7p9c"
        },
        {
          "url": "https://cna.openjsf.org/security-advisories.html"
        }
      ],
      "title": "@fastify/express vulnerable to middleware path doubling causing authentication bypass in child plugin scopes",
      "x_generator": {
        "engine": "cve-kit 1.0.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "ce714d77-add3-4f53-aff5-83d477b104bb",
    "assignerShortName": "openjs",
    "cveId": "CVE-2026-33807",
    "datePublished": "2026-04-15T09:52:26.838Z",
    "dateReserved": "2026-03-23T19:48:48.715Z",
    "dateUpdated": "2026-04-15T13:09:45.259Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

CVE-2026-33807 (GCVE-0-2026-33807)

Vulnerability from cvelistv5 – Published: 2026-04-15 09:52 – Updated: 2026-04-15 13:09
VLAI?
Title
@fastify/express vulnerable to middleware path doubling causing authentication bypass in child plugin scopes
Summary
@fastify/express v4.0.4 and earlier contains a path handling bug in the onRegister function that causes middleware paths to be doubled when inherited by child plugins. When a child plugin is registered with a prefix that matches a middleware path, the middleware path is prefixed a second time, causing it to never match incoming requests. This results in complete bypass of Express middleware security controls, including authentication, authorization, and rate limiting, for all routes defined within affected child plugin scopes. No special configuration or request crafting is required. Upgrade to @fastify/express v4.0.5 or later.
Severity ?
9.1 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CWE
  • CWE-436 - Interpretation Conflict
Assigner
References
Impacted products
Vendor Product Version
fastify @fastify/express Affected: 0 , < 4.0.5 (semver)
Unaffected: 4.0.5 (semver)
Create a notification for this product.
Credits
FredKSchott mcollina UlisesGascon climba03003
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-33807",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-04-15T13:09:41.621709Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-04-15T13:09:45.259Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/fastify/fastify-express/security/advisories/GHSA-hrwm-hgmj-7p9c"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "packageURL": "pkg:npm/@fastify/express",
          "product": "@fastify/express",
          "vendor": "fastify",
          "versions": [
            {
              "lessThan": "4.0.5",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "4.0.5",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "reporter",
          "value": "FredKSchott"
        },
        {
          "lang": "en",
          "type": "remediation developer",
          "value": "mcollina"
        },
        {
          "lang": "en",
          "type": "remediation reviewer",
          "value": "UlisesGascon"
        },
        {
          "lang": "en",
          "type": "remediation reviewer",
          "value": "climba03003"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003ch3\u003e\u003cspan\u003e\u003cspan\u003e@fastify/express v4.0.4 and earlier contains a path handling bug in the onRegister function that causes middleware paths to be doubled when inherited by child plugins. When a child plugin is registered with a prefix that matches a middleware path, the middleware path is prefixed a second time, causing it to never match incoming requests. This results in complete bypass of Express middleware security controls, including authentication, authorization, and rate limiting, for all routes defined within affected child plugin scopes. No special configuration or request crafting is required.\u003cbr\u003e\u003c/span\u003e\u003cspan\u003e\u003cbr\u003eUpgrade to @fastify/express v4.0.5 or later.\u003c/span\u003e\u003c/span\u003e\u003c/h3\u003e"
            }
          ],
          "value": "@fastify/express v4.0.4 and earlier contains a path handling bug in the onRegister function that causes middleware paths to be doubled when inherited by child plugins. When a child plugin is registered with a prefix that matches a middleware path, the middleware path is prefixed a second time, causing it to never match incoming requests. This results in complete bypass of Express middleware security controls, including authentication, authorization, and rate limiting, for all routes defined within affected child plugin scopes. No special configuration or request crafting is required.\n\nUpgrade to @fastify/express v4.0.5 or later."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 9.1,
            "baseSeverity": "CRITICAL",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N",
            "version": "3.1"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-436",
              "description": "CWE-436: Interpretation Conflict",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-04-15T09:55:50.627Z",
        "orgId": "ce714d77-add3-4f53-aff5-83d477b104bb",
        "shortName": "openjs"
      },
      "references": [
        {
          "url": "https://github.com/fastify/fastify-express/security/advisories/GHSA-hrwm-hgmj-7p9c"
        },
        {
          "url": "https://cna.openjsf.org/security-advisories.html"
        }
      ],
      "title": "@fastify/express vulnerable to middleware path doubling causing authentication bypass in child plugin scopes",
      "x_generator": {
        "engine": "cve-kit 1.0.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "ce714d77-add3-4f53-aff5-83d477b104bb",
    "assignerShortName": "openjs",
    "cveId": "CVE-2026-33807",
    "datePublished": "2026-04-15T09:52:26.838Z",
    "dateReserved": "2026-03-23T19:48:48.715Z",
    "dateUpdated": "2026-04-15T13:09:45.259Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

CVE-2026-33808 (GCVE-0-2026-33808)

Vulnerability from cvelistv5 – Published: 2026-04-15 09:29 – Updated: 2026-04-15 13:10
VLAI?
Title
@fastify/express vulnerable to middleware authentication bypass via URL normalization gaps (duplicate slashes and semicolons)
Summary
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. PatchesUpgrade to @fastify/express v4.0.5 or later.
Severity ?
9.1 (Critical)
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
CWE
  • CWE-436 - Interpretation Conflict
Assigner
References
Impacted products
Vendor Product Version
fastify @fastify/express Affected: 0 , < 4.0.5 (semver)
Unaffected: 4.0.5 (semver)
Create a notification for this product.
Credits
FredKSchott mcollina UlisesGascon climba03003
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-33808",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-04-15T13:10:17.328470Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-04-15T13:10:24.054Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/fastify/fastify-express/security/advisories/GHSA-6hw5-45gm-fj88"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "packageURL": "pkg:npm/@fastify/express",
          "product": "@fastify/express",
          "vendor": "fastify",
          "versions": [
            {
              "lessThan": "4.0.5",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "4.0.5",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "reporter",
          "value": "FredKSchott"
        },
        {
          "lang": "en",
          "type": "remediation developer",
          "value": "mcollina"
        },
        {
          "lang": "en",
          "type": "remediation reviewer",
          "value": "UlisesGascon"
        },
        {
          "lang": "en",
          "type": "remediation reviewer",
          "value": "climba03003"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003ch3\u003eImpact\u003c/h3\u003e@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.\u003cbr\u003e\u003cbr\u003e\u003ch3\u003ePatches\u003c/h3\u003eUpgrade to @fastify/express v4.0.5 or later."
            }
          ],
          "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."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 9.1,
            "baseSeverity": "CRITICAL",
            "exploitMaturity": "NOT_DEFINED",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
            "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",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "HIGH",
            "vulnIntegrityImpact": "HIGH",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-436",
              "description": "CWE-436: Interpretation Conflict",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-04-15T09:29:46.091Z",
        "orgId": "ce714d77-add3-4f53-aff5-83d477b104bb",
        "shortName": "openjs"
      },
      "references": [
        {
          "url": "https://github.com/fastify/fastify-express/security/advisories/GHSA-6hw5-45gm-fj88"
        },
        {
          "url": "https://cna.openjsf.org/security-advisories.html"
        }
      ],
      "title": "@fastify/express vulnerable to middleware authentication bypass via URL normalization gaps (duplicate slashes and semicolons)",
      "x_generator": {
        "engine": "cve-kit 1.0.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "ce714d77-add3-4f53-aff5-83d477b104bb",
    "assignerShortName": "openjs",
    "cveId": "CVE-2026-33808",
    "datePublished": "2026-04-15T09:29:46.091Z",
    "dateReserved": "2026-03-23T19:48:48.715Z",
    "dateUpdated": "2026-04-15T13:10:24.054Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}