CVE-2026-53718
Envoy Gateway custom backendRef cross-namespace ReferenceGrant bypass
- State
- Published
- Severity
- 6.4 Medium
- Published
- Sep 14, 2026
- Updated
- Sep 15, 2026
- Reserved
- Jun 10, 2026
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, 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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 6.4 Medium | CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:L | GitHub_M |
Weaknesses
- CWE-862 Missing Authorization
Affected Products
| Product | Versions |
|---|---|
gatewayenvoyproxy |
|
References
- https://github.com/envoyproxy/gateway/security/advisories/GHSA-fcrp-7gc2-93g7
- https://github.com/envoyproxy/gateway/pull/9171
- https://github.com/envoyproxy/gateway/pull/9172
- https://github.com/envoyproxy/gateway/pull/9173
- https://github.com/envoyproxy/gateway/commit/5a78db82b7cf4fc5bebbeda2c50952892038a464
- https://github.com/envoyproxy/gateway/commit/96e2b750868a459ace4b8b68e6a6e4fb0152b9b7
- https://github.com/envoyproxy/gateway/commit/b4737180c7e597490c6363075c565fa8cf24eead
- https://github.com/envoyproxy/gateway/releases/tag/v1.7.4
- https://github.com/envoyproxy/gateway/releases/tag/v1.8.1
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