Envoy Gateway custom backendRef cross-namespace ReferenceGrant bypass

中 6.4CVE-2026-53718 · BIT-envoy-gateway-2026-53718 · GHSA-fcrp-7gc2-93g7 · 14/09/2026 公開 · 25/09/2026 更新

要点

CVE-2026-53718 は github.com/envoyproxy/gateway に影響する深刻度「中」 (CVSS 6.4) の脆弱性です。
今後30日間に悪用される確率（EPSS）：0.41%（全脆弱性の 35.6% より高い）。
対処：1.8.1, 1.7.4 以降に更新してください。

パッケージ	影響を受けるバージョン	修正済みバージョン
github.com/envoyproxy/gateway Go	`≥ 1.8.0-rc.0, < 1.8.1< 1.7.4`	`1.8.11.7.4`

概要

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 1.8.1

NVD の説明

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 extension-managed custom backendRef to reference a backend resource in another namespace without a matching Gateway API ReferenceGrant in the target namespace. The custom-backend branch in internal/gatewayapi/route.go omits validateBackendNamespace, allowing the route-owning namespace to bind to and use the resource without the backend namespace owner's consent and violating the Gateway API cross-namespace authorization model. This issue is fixed in versions 1.7.4 and 1.8.1.