CVE-2026-2880 — @fastify/middie has an improper path normalization vulnerability
A vulnerability in @fastify/middie versions < 9.2.0 can result in authentication/authorization bypass when using path-scoped middleware (for example, app.use('/secret', auth)). …
Published: 2026-02-27 · CVSS: 8.2 · CVSS 4.0
A vulnerability in @fastify/middie versions < 9.2.0 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.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7