FKIE_CVE-2026-84428

Vulnerability from fkie_nvd - Published: 2026-09-04 11:17 - Updated: 2026-09-15 19:54
Severity
7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Summary
fastify versions before 5.12.2 implement the case-insensitive nature of HTTP header names by lowercasing names in a route's header schema before compiling it, but the transformation is incomplete: it lowercases the properties keys and the root-level required array, and does not lowercase the trigger and dependent names inside the JSON Schema Draft 7 dependencies keyword. Because Node stores request header names in lowercase, a canonical-case dependency such as requiring an authentication header whenever a privileged-mode header is present never matches, and the presence assertion is silently skipped. An unauthenticated remote client can therefore send the header that activates a privileged branch while omitting the header the dependency was meant to require, bypassing the conditional check. Users should upgrade to fastify 5.12.2 or later.
References
ce714d77-add3-4f53-aff5-83d477b104bbhttps://cna.openjsf.org/security-advisories.htmlThird Party Advisory
ce714d77-add3-4f53-aff5-83d477b104bbhttps://github.com/fastify/fastify/security/advisories/GHSA-9q9j-q6p8-xq58Mitigation, Vendor Advisory
Impacted products
Vendor Product Version
fastify fastify *
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "packageURL": "pkg:npm/fastify",
          "product": "fastify",
          "vendor": "fastify",
          "versions": [
            {
              "lessThan": "5.12.2",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "5.12.2",
              "versionType": "semver"
            }
          ]
        }
      ],
      "source": "ce714d77-add3-4f53-aff5-83d477b104bb"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:fastify:fastify:*:*:*:*:*:node.js:*:*",
              "matchCriteriaId": "44437B15-E71B-4EDB-A998-E6A82C402616",
              "versionEndExcluding": "5.12.2",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "fastify versions before 5.12.2 implement the case-insensitive nature of HTTP header names by lowercasing names in a route\u0027s header schema before compiling it, but the transformation is incomplete: it lowercases the properties keys and the root-level required array, and does not lowercase the trigger and dependent names inside the JSON Schema Draft 7 dependencies keyword. Because Node stores request header names in lowercase, a canonical-case dependency such as requiring an authentication header whenever a privileged-mode header is present never matches, and the presence assertion is silently skipped. An unauthenticated remote client can therefore send the header that activates a privileged branch while omitting the header the dependency was meant to require, bypassing the conditional check. Users should upgrade to fastify 5.12.2 or later."
    }
  ],
  "id": "CVE-2026-84428",
  "lastModified": "2026-09-15T19:54:32.420",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 7.5,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "NONE",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 3.6,
        "source": "ce714d77-add3-4f53-aff5-83d477b104bb",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-84428",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-09-04T16:04:59.730612Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-09-04T11:17:19.317",
  "references": [
    {
      "source": "ce714d77-add3-4f53-aff5-83d477b104bb",
      "tags": [
        "Third Party Advisory"
      ],
      "url": "https://cna.openjsf.org/security-advisories.html"
    },
    {
      "source": "ce714d77-add3-4f53-aff5-83d477b104bb",
      "tags": [
        "Mitigation",
        "Vendor Advisory"
      ],
      "url": "https://github.com/fastify/fastify/security/advisories/GHSA-9q9j-q6p8-xq58"
    }
  ],
  "sourceIdentifier": "ce714d77-add3-4f53-aff5-83d477b104bb",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-178"
        }
      ],
      "source": "ce714d77-add3-4f53-aff5-83d477b104bb",
      "type": "Secondary"
    }
  ]
}



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