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CVE-2026-53718 (GCVE-0-2026-53718)

Vulnerability from cvelistv5 – Published: 2026-09-14 20:12 – Updated: 2026-09-15 13:55
VLAI
Title
Envoy Gateway custom backendRef cross-namespace ReferenceGrant bypass
Summary
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.
Severity
6.4 (Medium)
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:L
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-09-15 13:25 UTC
CWE
Assigner
References
Impacted products
Vendor Product Version CPE status
envoyproxy gateway Affected: < 1.7.4
Affected: >= 1.8.0-rc.0, < 1.8.1
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