Description

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.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.4",
  "pubDate": "2026-09-14T21:17:12.677Z",
  "pubdate": "2026-09-14T21:17:12.677Z",
  "executiveSummary": "Envoy Gateway is susceptible to an authentication bypass vulnerability affecting the xDS gRPC server when deployed in GatewayNamespaceMode (provider.kubernetes.deploy.type=GatewayNamespace).\nThe vulnerability stems from an incomplete implementation of JWT authentication interceptors, which fail to protect unary gRPC methods and specific streaming request types.\nAny pod with network connectivity to port 18000 can exploit these unauthenticated paths to perform unauthorized retrieval of sensitive configuration data.\nThe impact includes the exposure of TLS private keys, backend service endpoints, and complex routing configurations.\nThis vulnerability is critical as it allows unauthorized actors to perform reconnaissance and potentially intercept sensitive traffic by compromising the control plane communication.\nThe flaw affects Envoy Gateway versions prior to 1.7.4 and 1.8.1.\nExploitation requires no special privileges beyond network reachability to the control plane port.",
  "technicalDetails": "The root cause of this vulnerability lies in the improper implementation of gRPC interceptors within the xDS server component of Envoy Gateway, specifically when configured in GatewayNamespaceMode. The security implementation relies on a JWT StreamInterceptor, which is insufficient for complete protection.\nFirst, the implementation lacks a corresponding UnaryInterceptor, leaving every unary Fetch RPC entirely unauthenticated. Consequently, any caller can invoke these methods without presenting a valid JWT, bypassing the security policy defined for the control plane.\nSecond, the existing StreamInterceptor contains a logic flaw in its type assertion mechanism. It is programmed to validate only discoveryv3.DeltaDiscoveryRequest messages. When the server receives a discoveryv3.DiscoveryRequest (associated with the State-of-the-World/SotW protocol), the type assertion fails, and the interceptor inadvertently returns a success status instead of rejecting the request. This permits unauthenticated access to the streaming interface.\nThe attack flow proceeds as follows: An attacker identifies an Envoy Gateway instance with network access to port 18000. By targeting either the unauthenticated unary endpoints or utilizing the SotW protocol for streaming requests, the attacker initiates a standard xDS discovery process. Because the authentication middleware does not validate these specific request types, the Envoy Gateway responds with the requested configuration data.\nThrough this process, an attacker can access sensitive xDS resources, including StreamSecrets (leaking TLS private keys), StreamAggregatedResources, StreamClusters, StreamEndpoints, StreamRoutes, and StreamListeners. Accessing this information provides the attacker with a comprehensive map of the infrastructure, credentials for traffic interception, and the ability to identify internal service topologies.\nThis vulnerability affects Envoy Gateway versions prior to 1.7.4 and 1.8.1. The failure effectively renders the intended JWT-based access control mechanism null for the majority of xDS discovery operations, providing a broad surface for information disclosure that can lead to deeper infrastructure compromise."
}