CVE-2026-22031— Fastify Middie Middleware Path Bypass
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I. Basic Information for CVE-2026-22031
Vulnerability Information
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Vulnerability Title
Fastify Middie Middleware Path Bypass
Source: NVD (National Vulnerability Database)
Vulnerability Description
@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.
Source: NVD (National Vulnerability Database)
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:L
Source: NVD (National Vulnerability Database)
Vulnerability Type
URL编码处理不恰当(Hex编码)
Source: NVD (National Vulnerability Database)
Vulnerability Title
@fastify/middie 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
@fastify/middie是Fastify开源的一个中间件引擎。 @fastify/middie 9.1.0之前版本存在安全漏洞，该漏洞源于路径前缀匹配不当，可能导致中间件绕过。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
II. Public POCs for CVE-2026-22031
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- Fastify Middie Middleware Path Bypass · Advisory · fastify/middie · GitHubx_refsource_CONFIRM
- https://nvd.nist.gov/vuln/detail/CVE-2026-22031
IV. Related Vulnerabilities
Same vendor: fastify
- CVE-2026-33807
@fastify/express vulnerable to middleware path doubling caus - CVE-2026-33808
@fastify/express vulnerable to middleware authentication byp - CVE-2026-33806
fastify vulnerable to Body Schema Validation Bypass via Lead - CVE-2026-3635
Fastify request.protocol and request.host spoofable via X-Fo - CVE-2026-3419
Fastify's Missing End Anchor in "subtypeNameReg" Allows Malf
Same weakness: CWE-177
- CVE-2026-6414
@fastify/static vulnerable to route guard bypass via encoded - CVE-2026-29045
Hono: Arbitrary file access via serveStatic vulnerability - CVE-2026-22037
@fastify/express vulnerable to Improper Handling of URL Enco - CVE-2025-11990
Improper Handling of URL Encoding (Hex Encoding) in GitLab - CVE-2024-48866
QTS, QuTS hero
V. Comments for CVE-2026-22031
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