GHSA-267c-6grr-h53f

### Impact

App Router applications that rely on middleware or proxy-based checks for authorization can allow unauthorized access through transport-specific route variants used for segment prefetching. In affected configurations, specially crafted `.rsc` and segment-prefetch URLs can resolve to the same page without being matched by the intended middleware rule, which can allow protected content to be reached without the expected authorization check.

### Fix

We now include App Router transport variants when generating middleware matchers, so middleware protections are applied consistently to those requests as well as to the normal page URL.

### Workarounds

If you cannot upgrade immediately, enforce authorization in the underlying route or page logic instead of relying solely on middleware.