Skip to content
OpenAdvisories
Critical · 9.1 CVE-2026-6270 EUVD-2026-23241GHSA-72c6-fx6q-fr5w

@fastify/middie vulnerable to middleware authentication bypass in child plugin scopes

Published Apr 16, 2026 · Updated Apr 16, 2026 · Assigned by openjs

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.

Affected products

VendorProductAffectedFixed
@fastify/middie @fastify/middie < 9.3.2 9.3.2

Affected packages

EcosystemPackageAffectedFixedRecord
npm @fastify/middie < 9.3.2 9.3.2 GHSA-72c6-fx6q-fr5w

References