CVE-2026-33804

@fastify/middie versions 9.3.1 and earlier are vulnerable to middleware bypass when the deprecated Fastify ignoreDuplicateSlashes option is enabled. The middleware path matching logic does not account for duplicate slash normalization performed by Fastify's router, allowing requests with duplicat...

Interpretation Conflict

Overview @fastify/middie is a Middleware engine for Fastify Affected versions of this package are vulnerable to Interpretation Conflict in the propagation of middleware paths to child plugin scopes due to incorrect re-prefixing. An attacker can gain unauthorized access to protected routes by...

EUVD-2026-23235

@fastify/middie vulnerable to middleware bypass via deprecated ignoreDuplicateSlashes option...

GHSA-V9WW-2J6R-98Q6 @fastify/middie vulnerable to middleware bypass via deprecated ignoreDuplicateSlashes option

Impact @fastify/middie v9.3.1 and earlier does not read the deprecated but still functional top-level ignoreDuplicateSlashes option, only reading from routerOptions. This creates a normalization gap: Fastify's router normalizes duplicate slashes but middie does not, allowing middleware bypass via...

@fastify/middie vulnerable to middleware bypass via deprecated ignoreDuplicateSlashes option

Impact @fastify/middie v9.3.1 and earlier does not read the deprecated but still functional top-level ignoreDuplicateSlashes option, only reading from routerOptions. This creates a normalization gap: Fastify's router normalizes duplicate slashes but middie does not, allowing middleware bypass via...

CVE-2026-33804 @fastify/middie vulnerable to middleware bypass via deprecated ignoreDuplicateSlashes option

@fastify/middie versions 9.3.1 and earlier are vulnerable to middleware bypass when the deprecated Fastify ignoreDuplicateSlashes option is enabled. The middleware path matching logic does not account for duplicate slash normalization performed by Fastify's router, allowing requests with duplicat...

CVE-2026-33804

@fastify/middie versions 9.3.1 and earlier are vulnerable to middleware bypass when the deprecated Fastify ignoreDuplicateSlashes option is enabled. The middleware path matching logic does not account for duplicate slash normalization performed by Fastify's router, allowing requests with duplicat...

PT-2026-33320

Name of the Vulnerable Software and Affected Versions @fastify/middie versions prior to 9.3.2 Description Inherited middleware is not registered directly on child plugin engine instances. When authentication middleware is registered in a parent scope and child plugins are registered with...