FKIE_CVE-2026-22031

Vulnerability from fkie_nvd - Published: 2026-01-19 16:15 - Updated: 2026-03-13 14:40
Severity ?
8.4 (High) - CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:L
8.8 (High) - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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/d44cd56eb724490babf7b452fdbbdd37ea2effbaPatch
security-advisories@github.comhttps://github.com/fastify/middie/pull/245Issue Tracking, Patch
security-advisories@github.comhttps://github.com/fastify/middie/releases/tag/v9.1.0Product, Release Notes
security-advisories@github.comhttps://github.com/fastify/middie/security/advisories/GHSA-cxrg-g7r8-w69pExploit, Vendor Advisory
Impacted products
Vendor Product Version
openjsf \@fastify\/middie *
To clipboard 

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          "cpeMatch": [
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              "criteria": "cpe:2.3:a:openjsf:\\@fastify\\/middie:*:*:*:*:*:fastify:*:*",
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  "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."
    },
    {
      "lang": "es",
      "value": "@fastify/middie es el plugin que a\u00f1ade soporte de middleware potenciado a Fastify. Una vulnerabilidad de seguridad existe en @fastify/middie anterior a la versi\u00f3n 9.1.0 donde el middleware registrado con un prefijo de ruta espec\u00edfico puede ser evadido usando caracteres codificados en URL (p. ej., \u0027/%61dmin\u0027 en lugar de \u0027/admin\u0027). Mientras que el motor de middleware falla al coincidir con la ruta codificada y omite la ejecuci\u00f3n, el router subyacente de Fastify decodifica correctamente la ruta y coincide con el manejador de ruta, permitiendo a los atacantes acceder a puntos finales protegidos sin las restricciones del middleware. La versi\u00f3n 9.1.0 corrige el problema."
    }
  ],
  "id": "CVE-2026-22031",
  "lastModified": "2026-03-13T14:40:56.480",
  "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"
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        "exploitabilityScore": 1.8,
        "impactScore": 6.0,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      },
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 8.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 5.9,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
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  "published": "2026-01-19T16:15:54.310",
  "references": [
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      "source": "security-advisories@github.com",
      "tags": [
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    },
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      "source": "security-advisories@github.com",
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      "source": "security-advisories@github.com",
      "tags": [
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      "tags": [
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      "url": "https://github.com/fastify/middie/security/advisories/GHSA-cxrg-g7r8-w69p"
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  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Analyzed",
  "weaknesses": [
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      "description": [
        {
          "lang": "en",
          "value": "CWE-177"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Primary"
    }
  ]
}


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