FKIE_CVE-2026-22031

Vulnerability from fkie_nvd - Published: 2026-01-19 16:15 - Updated: 2026-01-19 16:15
Severity ?
8.4 (High) - CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:L
Summary
@fastify/middie is the plugin that adds middleware support on steroids to Fastify. A security vulnerability exists in @fastify/middie prior to version 9.1.0 where middleware registered with a specific path prefix can be bypassed using URL-encoded characters (e.g., `/%61dmin` instead of `/admin`). While the middleware engine fails to match the encoded path and skips execution, the underlying Fastify router correctly decodes the path and matches the route handler, allowing attackers to access protected endpoints without the middleware constraints. Version 9.1.0 fixes the issue.
References
security-advisories@github.comhttps://github.com/fastify/middie/commit/d44cd56eb724490babf7b452fdbbdd37ea2effba
security-advisories@github.comhttps://github.com/fastify/middie/pull/245
security-advisories@github.comhttps://github.com/fastify/middie/releases/tag/v9.1.0
security-advisories@github.comhttps://github.com/fastify/middie/security/advisories/GHSA-cxrg-g7r8-w69p
Impacted products
Vendor Product Version
To clipboard 

{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "@fastify/middie is the plugin that adds middleware support on steroids to Fastify. A security vulnerability exists in @fastify/middie prior to version 9.1.0 where middleware registered with a specific path prefix can be bypassed using URL-encoded characters (e.g., `/%61dmin` instead of `/admin`). While the middleware engine fails to match the encoded path and skips execution, the underlying Fastify router correctly decodes the path and matches the route handler, allowing attackers to access protected endpoints without the middleware constraints. Version 9.1.0 fixes the issue."
    }
  ],
  "id": "CVE-2026-22031",
  "lastModified": "2026-01-19T16:15:54.310",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "LOW",
          "baseScore": 8.4,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "CHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:L",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 6.0,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-01-19T16:15:54.310",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/fastify/middie/commit/d44cd56eb724490babf7b452fdbbdd37ea2effba"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/fastify/middie/pull/245"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/fastify/middie/releases/tag/v9.1.0"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/fastify/middie/security/advisories/GHSA-cxrg-g7r8-w69p"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Received",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-177"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Primary"
    }
  ]
}


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