CVE-2026-2880: @fastify/middie has Improper Path Normalization when Using Path-Scoped Middleware

A path normalization inconsistency in @fastify/middie can result in authentication/authorization bypass when using path-scoped middleware (for example, app.use('/secret', auth)).

When Fastify router normalization options are enabled (such as ignoreDuplicateSlashes, useSemicolonDelimiter, and related trailing-slash behavior), crafted request paths may bypass middleware checks while still being routed to protected handlers.