{"id":"BIT-envoy-gateway-2026-53718","summary":"Envoy Gateway custom backendRef cross-namespace ReferenceGrant bypass","details":"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.","aliases":["CVE-2026-53718","GHSA-fcrp-7gc2-93g7","GO-2026-6007"],"modified":"2026-09-21T09:40:33.033237034Z","published":"2026-09-21T08:54:59.902Z","database_specific":{"severity":"Medium","cpes":["cpe:2.3:a:envoyproxy:gateway:*:*:*:*:*:go:*:*"]},"references":[{"type":"WEB","url":"https://github.com/envoyproxy/gateway/commit/5a78db82b7cf4fc5bebbeda2c50952892038a464"},{"type":"WEB","url":"https://github.com/envoyproxy/gateway/commit/96e2b750868a459ace4b8b68e6a6e4fb0152b9b7"},{"type":"WEB","url":"https://github.com/envoyproxy/gateway/commit/b4737180c7e597490c6363075c565fa8cf24eead"},{"type":"WEB","url":"https://github.com/envoyproxy/gateway/pull/9171"},{"type":"WEB","url":"https://github.com/envoyproxy/gateway/pull/9172"},{"type":"WEB","url":"https://github.com/envoyproxy/gateway/pull/9173"},{"type":"WEB","url":"https://github.com/envoyproxy/gateway/releases/tag/v1.7.4"},{"type":"WEB","url":"https://github.com/envoyproxy/gateway/releases/tag/v1.8.1"},{"type":"WEB","url":"https://github.com/envoyproxy/gateway/security/advisories/GHSA-fcrp-7gc2-93g7"},{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-53718"}],"affected":[{"package":{"name":"envoy-gateway","ecosystem":"Bitnami","purl":"pkg:bitnami/envoy-gateway"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"1.7.4"},{"introduced":"1.8.0"},{"fixed":"1.8.1"}]}],"database_specific":{"source":"https://github.com/bitnami/vulndb/tree/main/data/envoy-gateway/BIT-envoy-gateway-2026-53718.json"},"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:L"}]}],"schema_version":"1.9.0"}