@fastify/express's middleware path doubling causes authentication bypass in child plugin scopes

Summary @fastify/express v4.0.4 contains a path handling bug in the onRegister function that causes middleware paths to be doubled when inherited by child plugins. This results in complete bypass of Express middleware security controls for all routes defined within child plugin scopes that share ...

GHSA-HRWM-HGMJ-7P9C @fastify/express's middleware path doubling causes authentication bypass in child plugin scopes

Summary @fastify/express v4.0.4 contains a path handling bug in the onRegister function that causes middleware paths to be doubled when inherited by child plugins. This results in complete bypass of Express middleware security controls for all routes defined within child plugin scopes that share ...

Interpretation Conflict

Overview @fastify/express is an Express compatibility layer for Fastify Affected versions of this package are vulnerable to Interpretation Conflict due to improper handling of middleware paths in the onRegister function. An attacker can gain unauthorized access to protected routes by exploiting t...

CVE-2026-33807

CVE-2026-33807 affects @fastify/express v4.0.4 and earlier. A path handling bug in onRegister doubles middleware paths when inherited by child plugins, causing the middleware to never match requests. This results in complete bypass of Express middleware security controls (authentication, authoriz...