{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "1.7.4"
              },
              {
                "introduced": "1.8.0-rc.0"
              },
              {
                "fixed": "1.8.1"
              }
            ],
            "source": [
              "AFFECTED_FIELD",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "introduced": "2de2611fdbbca83d4a1ede99417c90fcdead24d9"
            },
            {
              "fixed": "062b176235b72d339fac340d23dd37679b36dca6"
            },
            {
              "fixed": "097ab899b9d041452d02f15d738514eda10ea21b"
            },
            {
              "fixed": "5a78db82b7cf4fc5bebbeda2c50952892038a464"
            },
            {
              "fixed": "96e2b750868a459ace4b8b68e6a6e4fb0152b9b7"
            },
            {
              "fixed": "b4737180c7e597490c6363075c565fa8cf24eead"
            }
          ],
          "repo": "https://github.com/envoyproxy/gateway",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-fcrp-7gc2-93g7"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-862"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53718.json"
  },
  "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.",
  "id": "CVE-2026-53718",
  "modified": "2026-09-16T03:31:03.242781043Z",
  "published": "2026-09-14T20:12:12.224Z",
  "references": [
    {
      "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": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53718.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/envoyproxy/gateway/security/advisories/GHSA-fcrp-7gc2-93g7"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-53718"
    },
    {
      "type": "FIX",
      "url": "https://github.com/envoyproxy/gateway/commit/5a78db82b7cf4fc5bebbeda2c50952892038a464"
    },
    {
      "type": "FIX",
      "url": "https://github.com/envoyproxy/gateway/commit/96e2b750868a459ace4b8b68e6a6e4fb0152b9b7"
    },
    {
      "type": "FIX",
      "url": "https://github.com/envoyproxy/gateway/commit/b4737180c7e597490c6363075c565fa8cf24eead"
    },
    {
      "type": "FIX",
      "url": "https://github.com/envoyproxy/gateway/pull/9171"
    },
    {
      "type": "FIX",
      "url": "https://github.com/envoyproxy/gateway/pull/9172"
    },
    {
      "type": "FIX",
      "url": "https://github.com/envoyproxy/gateway/pull/9173"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Envoy Gateway custom backendRef cross-namespace ReferenceGrant bypass"
}