Spring gRPC SecurityContext leaks across requests upon authorization failure

When an authenticated user is denied access to a gRPC method, their authenticated identity remains bound to the gRPC worker thread and can be inherited by a subsequent unauthenticated request on the same thread. This may allow the subsequent user to gain escalated permissions.

Affected versions:
Spring gRPC: 1.0.0 - 1.0.2 (fixed in 1.0.3). Older, unsupported versions are also affected.