Description
A vulnerability in @fastify/middie versions < 9.2.0 can result in authentication/authorization bypass when using path-scoped middleware (for example, app.use('/secret', auth)).

When Fastify router normalization options are enabled (such as ignoreDuplicateSlashes, useSemicolonDelimiter, and related trailing-slash behavior), crafted request paths may bypass middleware checks while still being routed to protected handlers.
Published: 2026-02-27
Score: 8.2 High
EPSS: < 1% Very Low
KEV: No
Impact: Authentication/Authorization bypass via improper path normalization
Action: Immediate Patch
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-8p85-9qpw-fwgw @fastify/middie has Improper Path Normalization when Using Path-Scoped Middleware
History

Thu, 14 May 2026 15:45:00 +0000

Type Values Removed Values Added
First Time appeared Fastify fastify\/middie
CPEs cpe:2.3:a:openjsf:\@fastify\/middie:*:*:*:*:*:fastify:*:* cpe:2.3:a:fastify:fastify\/middie:*:*:*:*:*:node.js:*:*
Vendors & Products Openjsf
Openjsf \@fastify\/middie
Fastify fastify\/middie

Thu, 19 Mar 2026 17:45:00 +0000

Type Values Removed Values Added
First Time appeared Openjsf
Openjsf \@fastify\/middie
CPEs cpe:2.3:a:openjsf:\@fastify\/middie:*:*:*:*:*:fastify:*:*
Vendors & Products Openjsf
Openjsf \@fastify\/middie
Metrics cvssV3_1

{'score': 9.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N'}


Mon, 02 Mar 2026 12:15:00 +0000

Type Values Removed Values Added
First Time appeared Fastify
Fastify middie
Vendors & Products Fastify
Fastify middie

Fri, 27 Feb 2026 19:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Fri, 27 Feb 2026 18:45:00 +0000

Type Values Removed Values Added
Description A vulnerability in @fastify/middie versions < 9.2.0 can result in authentication/authorization bypass when using path-scoped middleware (for example, app.use('/secret', auth)). When Fastify router normalization options are enabled (such as ignoreDuplicateSlashes, useSemicolonDelimiter, and related trailing-slash behavior), crafted request paths may bypass middleware checks while still being routed to protected handlers.
Title @fastify/middie has an improper path normalization vulnerability
Weaknesses CWE-20
References
Metrics cvssV4_0

{'score': 8.2, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N'}


Subscriptions

Fastify Fastify\/middie Middie
cve-icon MITRE

Status: PUBLISHED

Assigner: openjs

Published:

Updated: 2026-02-27T18:56:02.979Z

Reserved: 2026-02-20T16:50:56.850Z

Link: CVE-2026-2880

cve-icon Vulnrichment

Updated: 2026-02-27T18:55:51.355Z

cve-icon NVD

Status : Analyzed

Published: 2026-02-27T19:16:12.807

Modified: 2026-05-14T15:41:44.877

Link: CVE-2026-2880

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-04-17T14:00:15Z

Weaknesses