@fastify/middie versions 9.3.1 and earlier do not register inherited middleware directly on child plugin engine instances. When a Fastify application registers authentication middleware in a parent scope and then registers child plugins with @fastify/middie, the child scope does not inherit the parent middleware. This allows unauthenticated requests to reach routes defined in child plugin scopes, bypassing authentication and authorization checks. Upgrade to @fastify/middie 9.3.2 to fix this issue. There are no workarounds.
History

Thu, 16 Apr 2026 15:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Thu, 16 Apr 2026 14:00:00 +0000

Type Values Removed Values Added
Description @fastify/middie versions 9.3.1 and earlier do not register inherited middleware directly on child plugin engine instances. When a Fastify application registers authentication middleware in a parent scope and then registers child plugins with @fastify/middie, the child scope does not inherit the parent middleware. This allows unauthenticated requests to reach routes defined in child plugin scopes, bypassing authentication and authorization checks. Upgrade to @fastify/middie 9.3.2 to fix this issue. There are no workarounds.
Title @fastify/middie vulnerable to middleware authentication bypass in child plugin scopes
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'}


cve-icon MITRE

Status: PUBLISHED

Assigner: openjs

Published:

Updated: 2026-04-16T14:24:26.764Z

Reserved: 2026-04-14T11:08:51.828Z

Link: CVE-2026-6270

cve-icon Vulnrichment

Updated: 2026-04-16T14:24:22.614Z

cve-icon NVD

Status : Received

Published: 2026-04-16T14:16:19.433

Modified: 2026-04-16T14:16:19.433

Link: CVE-2026-6270

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.