CVE-2026-22031

@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.
Configurations

Configuration 1 (hide)

cpe:2.3:a:fastify:fastify\/middie:*:*:*:*:*:node.js:*:*

History

14 May 2026, 15:41

Type Values Removed Values Added
CPE cpe:2.3:a:openjsf:\@fastify\/middie:*:*:*:*:*:fastify:*:* cpe:2.3:a:fastify:fastify\/middie:*:*:*:*:*:node.js:*:*
First Time Fastify fastify\/middie
Fastify
Summary
  • (es) @fastify/middie es el plugin que añade soporte de middleware potenciado a Fastify. Una vulnerabilidad de seguridad existe en @fastify/middie anterior a la versión 9.1.0 donde el middleware registrado con un prefijo de ruta específico puede ser evadido usando caracteres codificados en URL (p. ej., '/%61dmin' en lugar de '/admin'). Mientras que el motor de middleware falla al coincidir con la ruta codificada y omite la ejecución, 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 versión 9.1.0 corrige el problema.

13 Mar 2026, 14:40

Type Values Removed Values Added
CPE cpe:2.3:a:openjsf:\@fastify\/middie:*:*:*:*:*:fastify:*:*
First Time Openjsf \@fastify\/middie
Openjsf
References () https://github.com/fastify/middie/commit/d44cd56eb724490babf7b452fdbbdd37ea2effba - () https://github.com/fastify/middie/commit/d44cd56eb724490babf7b452fdbbdd37ea2effba - Patch
References () https://github.com/fastify/middie/pull/245 - () https://github.com/fastify/middie/pull/245 - Issue Tracking, Patch
References () https://github.com/fastify/middie/releases/tag/v9.1.0 - () https://github.com/fastify/middie/releases/tag/v9.1.0 - Product, Release Notes
References () https://github.com/fastify/middie/security/advisories/GHSA-cxrg-g7r8-w69p - () https://github.com/fastify/middie/security/advisories/GHSA-cxrg-g7r8-w69p - Exploit, Vendor Advisory

19 Jan 2026, 16:15

Type Values Removed Values Added
New CVE

Information

Published : 2026-01-19 16:15

Updated : 2026-05-14 15:41


NVD link : CVE-2026-22031

Mitre link : CVE-2026-22031

CVE.ORG link : CVE-2026-22031


JSON object : View

Products Affected

fastify

  • fastify\/middie
CWE
CWE-177

Improper Handling of URL Encoding (Hex Encoding)