CVE-2026-85184

@fastify/middie vulnerable to path-scoped middleware bypass via absolute-form request target

Published Sep 4, 2026 CVSS 3.1 · 9.1 Critical EPSS < 1% KEV · Not listed
Description
@fastify/middie versions >= 9.1.0 and before 9.3.4 decide whether to run path-scoped middleware by matching against the raw request target, while the Fastify router resolves an absolute-form request target to its path before dispatching. Because the two layers evaluate different strings, a request using an absolute-form target reaches the route handler while the path-scoped middleware, such as authentication or authorization, is skipped. An unauthenticated network attacker can use this to bypass path-based access controls in a Fastify application that relies on middie for those controls. Users should upgrade to @fastify/middie 9.3.4 or later.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Fastify fastify\/middie
CPEs cpe:2.3:a:fastify:fastify\/middie:*:*:*:*:*:node.js:*:*
Vendors & Products Fastify fastify\/middie
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Fastify
Fastify fastify/middie
Vendors & Products Fastify
Fastify fastify/middie
Type Values Removed Values Added
Description @fastify/middie versions >= 9.1.0 and before 9.3.4 decide whether to run path-scoped middleware by matching against the raw request target, while the Fastify router resolves an absolute-form request target to its path before dispatching. Because the two layers evaluate different strings, a request using an absolute-form target reaches the route handler while the path-scoped middleware, such as authentication or authorization, is skipped. An unauthenticated network attacker can use this to bypass path-based access controls in a Fastify application that relies on middie for those controls. Users should upgrade to @fastify/middie 9.3.4 or later.
Title @fastify/middie vulnerable to path-scoped middleware bypass via absolute-form request target
Weaknesses CWE-436
References
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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
openjs
Published
Updated
Sep 4, 2026, 7:36 PM
Reserved
Sep 3, 2026, 11:39 AM
Status
Analyzed
Published
Sep 4, 2026, 10:17 AM
Modified
Sep 15, 2026, 8:02 PM