CVE-2026-112712
CVE-2026-112712 · @fastify/middie vulnerable to path-scoped middleware bypass via scope prefix mismatch
This page contains facts from public vulnerability sources. Check the original advisory before updating.
@fastify/middie is the Express-style middleware engine for Fastify. In versions from 9.0.0 through 9.3.5, the use() function joined a path-scoped middleware's mount path to the plugin scope prefix in a way that could diverge from the path Fastify's router serves, most often when the scope prefix ended in a slash, and also for array mount paths and for mount paths written without a leading slash. When the two paths disagreed, the middleware was silently skipped while the route handler still ran, so path-scoped middleware such as authentication, authorization, or rate limiting could be bypassed by a single unauthenticated request. The issue is fixed in @fastify/middie 9.3.6, and users should upgrade to 9.3.6 or later. As a workaround, enforce authorization in a Fastify hook such as preHandler that runs after the router has resolved the request.
CVSS 9.1 · Critical · EPSS 0.3% · Fix available
- Published
- Updated
Affected products and versions
@fastify/middie
- Versions
- ≥ 9.0.0, < 9.3.6: Affected (semver)
- 9.3.6: Not affected (semver)
Update to 9.3.6