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CVE-2026-53718— Envoy Gateway custom backendRef cross-namespace ReferenceGrant bypass

Quick assessment

Affected
envoyproxy gateway
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Envoy Gateway 是一个开源项目，用于将 Envoy Proxy 作为独立应用或基于 Kubernetes 的应用网关进行管理和配置。在 1.7.4 和 1.8.1 版本之前，HTTPRoute 可以在目标命名空间中缺少对应的 Gateway API ReferenceGrant 的情况下，使用扩展管理的自定义 backendRef 来引用其他命名空间中的后端资源。该问题源于 中 custom-backend 分支遗漏了对 的调用，导致路由所在命名空间能够在未获得后端命名空间所有者授权的情况下绑定并使用该

CVSS 6.4 · Medium EPSS 0.04% · P13
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I. Basic Information for CVE-2026-53718

Vulnerability Information
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Vulnerability Title
Envoy Gateway custom backendRef cross-namespace ReferenceGrant bypass
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
授权机制缺失
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
envoyproxy gateway < 1.7.4 -

II. Public POCs for CVE-2026-53718

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III. Intelligence Information for CVE-2026-53718

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Patches & Fixes for CVE-2026-53718 (3)

Vendor Advisories for CVE-2026-53718 (1)

Vendor Pages for CVE-2026-53718 (2)

Same Patch Batch · envoyproxy · 2026-09-14 · 7 CVEs total

CVE-2026-53713 9.1 CRITICAL Envoy Gateway: Authentication Bypass via Improper Input Validation in EnvoyExtensionPolicy
CVE-2026-53714 7.4 HIGH Envoy Gateway: xDS Control Plane Information Disclosure when Envoy Gateway operates in Gat
CVE-2026-53716 6.5 MEDIUM Envoy Gateway: Wasm HTTP fetch decompresses gzip without output-size limit
CVE-2026-53719 6.5 MEDIUM Envoy Gateway: Nil-dereference when SecurityPolicy targets TCPRoute without spec.authoriza
CVE-2026-53717 6.5 MEDIUM Envoy Gateway: OCI layer extraction allocates make([]byte, h.Size) from untrusted tar head
CVE-2026-53715 5.3 MEDIUM Envoy Gateway: Wasm cache ServeHTTP reads mappingPath2Cache without lock

IV. Related Vulnerabilities

Same product: gateway
Same vendor: envoyproxy
Same weakness: CWE-862

V. Comments for CVE-2026-53718

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