CVE-2026-50202

### Summary The JWT signing key cache in `TokenKeyResolver` uses `kid` as the sole cache key without namespacing by authority. In applications with multiple `JwtBearer` schemes pointing to different identity providers, a key fetched for one scheme can satisfy token validation for another. Additionally, cached keys have no expiration, so rotated or revoked keys remain trusted until the application process restarts. ### Impact In multi-scheme deployments, an attacker who controls one identity provider's signing key can forge tokens accepted by other schemes within the same application. For all applications using `TokenKeyResolver`, a signing key removed from the identity provider's JWKS endpoint remains trusted indefinitely. ### Mitigations If an immediate upgrade is not possible: - In multi-scheme deployments, configure only one `JwtBearer` scheme per application when different identity providers are required. - Restart the application process after an identity provider signing key rotation to clear stale cached keys.