Nest is a framework for building scalable Node.js server-side applications. Prior to 11.1.24, an authentication bypass vulnerability exists in @nestjs/platform-fastify. When middleware is registered through NestJS's MiddlewareConsumer.forRoutes() API on the Fastify adapter, an unauthenticated client can bypass the Nest middleware registered for that route by simply appending a trailing slash (/) to the request URL. This bypass works on the default Fastify adapter configuration. This vulnerability is fixed in 11.1.24.

Affected: npm: @nestjs/platform-fastify

### Impact

An authentication bypass vulnerability exists in `@nestjs/platform-fastify` (confirmed on version `11.1.24`, the latest available release at time of report). When middleware is registered through NestJS's `MiddlewareConsumer.forRoutes()` API on the Fastify adapter, an unauthenticated client can bypass the Nest middleware registered for that route by simply appending a trailing slash (`/`) to the request URL.

This bypass works on the **default Fastify adapter configuration** — no special router options need to be enabled. Applications using the standard CRUD route shape (`GET /resource` and `GET /resource/:id`) are affected when they protect those routes with `MiddlewareConsumer.forRoutes()` middleware.

### Patches

Fixed in `@nestjs/platform-fastify@11.1.24`

### References

Kudos goes to @a-tt-om