CVE-2026-53714

### Impact When Envoy Gateway runs in GatewayNamespaceMode (`provider.kubernetes.deploy.type=GatewayNamespace`), the xDS gRPC server is configured with a `StreamInterceptor` for JWT authentication but no UnaryInterceptor. The go-control-plane xDS server exposes both streaming and unary (Fetch) RPC methods for all registered discovery services. Since there is no unary interceptor, these Fetch endpoints are completely unauthenticated. Additionally, the JWT authentication interceptor in GatewayNamespaceMode only validates tokens when the received gRPC message is of type `discoveryv3.DeltaDiscoveryRequest` . If the message is a `discoveryv3.DiscoveryRequest` — used by the State-of-the-World (SotW) xDS protocol — the type assertion fails, the validation block is skipped entirely, and RecvMsg returns nil (success) without any authentication. Any pod in the cluster that can reach the xDS server (port 18000) can use the SotW protocol to bypass JWT authentication and access: * TLS private keys via StreamSecrets (SDS) * All xDS resources via StreamAggregatedResources (ADS) * Backend endpoints via StreamClusters / StreamEndpoints (CDS/EDS) * Routing rules via StreamRoutes / StreamListeners (RDS/LDS) ### Credits Envoy Gateway thanks @dashingDragon and @Donjon-Cerberus for reporting this issue.

Envoy Gateway is an open source project for managing Envoy Proxy as a standalone or Kubernetes-based application gateway. Prior to 1.7.4 and 1.8.1, the xDS gRPC server in GatewayNamespaceMode, configured through provider.kubernetes.deploy.type=GatewayNamespace, installs a JWT StreamInterceptor but no UnaryInterceptor, leaving every unary Fetch RPC unauthenticated. The streaming interceptor also authenticates only discoveryv3.DeltaDiscoveryRequest messages; a discoveryv3.DiscoveryRequest used by the State-of-the-World protocol fails the type assertion and returns success without JWT validation. Any pod that can reach port 18000 can use the unauthenticated unary or State-of-the-World paths to retrieve TLS private keys through StreamSecrets, all xDS resources through StreamAggregatedResources, backend endpoints through StreamClusters or StreamEndpoints, and routing configuration through StreamRoutes or StreamListeners. This issue is fixed in versions 1.7.4 and 1.8.1.

Envoy Gateway: xDS Control Plane Information Disclosure when operating in GatewayNamespaceMode in github.com/envoyproxy/gateway