Envoy Gateway custom backendRef cross-namespace ReferenceGrant bypass
### Impact Envoy Gateway accepts extension-managed custom backendRefs from an HTTPRoute to a backend resource in another namespace without requiring a matching Gateway API ReferenceGrant in the target namespace. This breaks the Gateway API cross-namespace consent model: the namespace that owns the referenced backend resource does not need to opt in with a ReferenceGrant before another namespace’s HTTPRoute can use that resource. ### Patches [1.7.4](https://github.com/envoyproxy/gateway/releases/tag/v1.7.4) [1.8.1](https://github.com/envoyproxy/gateway/releases/tag/v1.8.1)
describes (1)
Related CVEs.
| ID | severity | exploitable | ||
|---|---|---|---|---|
| CVE-2026-53718US | —OT elevated | — | ||
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, an HTTPRoute can use an extensio… | ||||
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