CVE-2026-53718: Github.com/envoyproxy/gateway Envoy Gateway Custom BackendRef Cross-namespace Vulnerability

MODERATE
Advisory Identifier: GHSA-fcrp-7gc2-93g7
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CVSS 6.4
CWE-862
Published
Advisory Summary

CVE-2026-53718 is a MODERATE (CVSS 6.4) envoy gateway custom backendref cross-namespace vulnerability (CWE-862: Missing Authorization) affecting Github.com/envoyproxy/gateway libraries in the Go ecosystem. The issue involves envoy gateway custom backendref cross-namespace referencegrant bypass. Remediation is available by upgrading affected packages to version 1.8.1, 1.7.4.

CVE-2026-53718 at a Glance

CVE Identifier CVE-2026-53718
GHSA Identifier GHSA-fcrp-7gc2-93g7
Severity MODERATE
CVSS v3.1 Base Score 6.4
CWE Classification CWE-862: Missing Authorization
Affected Product Github.com/envoyproxy/gateway
Package Ecosystem Go
Published Date
Last Updated

Security Impact

CVSS: 6.4

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:L).

Attack Vector Network (AV:N)
Attack Complexity High (AC:H)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity Low (I:L)
Availability Low (A:L)

How to Fix CVE-2026-53718

To remediate this vulnerability, upgrade all affected Github.com/envoyproxy/gateway dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

github.com/envoyproxy/gateway fixed: 1.8.1 
Upgrade github.com/envoyproxy/gateway to 1.8.1
github.com/envoyproxy/gateway fixed: 1.7.4 
Upgrade github.com/envoyproxy/gateway to 1.7.4
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for github.com/envoyproxy/gateway

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-53718, inspect your project dependencies for Github.com/envoyproxy/gateway:

inspect dependencies for github.com/envoyproxy/gateway

Analyze the terminal output to locate any version of Github.com/envoyproxy/gateway in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.8.1), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-862: Missing Authorization, where the product does not perform an authorization check when an actor attempts to access a resource or perform an action. In Github.com/envoyproxy/gateway, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Impact Envoy Gateway accepts extension-managed custom backendRefs from an HTTPRoute to a backend resource in another namespace without requiring a matching Gateway API ReferenceGrant in the target namespace. This breaks the Gateway API cross-namespace consent model: the namespace that owns the referenced backend resource does not need to opt in with a ReferenceGrant before another namespace’s HTTPRoute can use that resource. ### Patches [1.7.4](https://github.com/envoyproxy/gateway/releases/tag/v1.7.4) [1.8.1](https://github.com/envoyproxy/gateway/releases/tag/v1.8.1)

CVE-2026-53718 Affected Github.com/envoyproxy/gateway Versions

2 component(s)
Fixed Versions:
1.8.11.7.4
Product / Package Ecosystem Affected Versions Fixed Version
github.com/envoyproxy/gateway
golang/github.com/envoyproxy/gateway
Go
≥ 1.8.0-rc.0
< 1.8.1
1.8.1
github.com/envoyproxy/gateway
golang/github.com/envoyproxy/gateway
Go
< 1.7.4
1.7.4

References

GitHub Advisory / Wiki ADVISORY
https://github.com/envoyproxy/gateway/security/advisories/GHSA-fcrp-7gc2-93g7
Github.com/envoyproxy/gateway Source Repository REPOSITORY
https://github.com/envoyproxy/gateway

Frequently Asked Questions

What is CVE-2026-53718?
CVE-2026-53718 is a security vulnerability in Github.com/envoyproxy/gateway involving Envoy Gateway custom backendRef cross-namespace ReferenceGrant bypass under CWE-862: Missing Authorization.
Which Github.com/envoyproxy/gateway versions are affected?
Affected versions include releases prior to 1.8.1, 1.7.4 across affected packages: github.com/envoyproxy/gateway.
What version fixes CVE-2026-53718?
Upgrading to 1.8.1, 1.7.4 (or the latest patched release for your respective branch) resolves the vulnerability.
Is github.com/envoyproxy/gateway affected?
Yes, github.com/envoyproxy/gateway is affected in releases prior to 1.8.1, 1.7.4. Upgrade your dependency to 1.8.1, 1.7.4 or later.
What is the CVSS score of CVE-2026-53718?
CVE-2026-53718 has a CVSS v3.1 base score of 6.4 (MODERATE) with vector string CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:L.
What CWE is associated with CVE-2026-53718?
CVE-2026-53718 is classified under CWE-862: Missing Authorization (The product does not perform an authorization check when an actor attempts to access a resource or perform an action.).
How can I check Go dependencies for CVE-2026-53718?
Run the dependency tree command: 'inspect dependencies for github.com/envoyproxy/gateway'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-fcrp-7gc2-93g7",
  "modified" : "2026-07-16T19:14:50Z",
  "published" : "2026-07-16T19:14:50Z",
  "aliases" : [ "CVE-2026-53718" ],
  "summary" : "Envoy Gateway custom backendRef cross-namespace ReferenceGrant bypass",
  "details" : "### Impact\nEnvoy Gateway accepts extension-managed custom backendRefs from an HTTPRoute to a backend resource in another namespace without requiring a matching Gateway API ReferenceGrant in the target namespace. This breaks the Gateway API cross-namespace consent model: the namespace that owns the referenced backend resource does not need to opt in with a ReferenceGrant before another namespace’s HTTPRoute can use that resource.\n\n### Patches\n[1.7.4](https://github.com/envoyproxy/gateway/releases/tag/v1.7.4)\n[1.8.1](https://github.com/envoyproxy/gateway/releases/tag/v1.8.1)",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:L"
  } ],
  "affected" : [ {
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    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
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      }, {
        "fixed" : "1.8.1"
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  }, {
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    },
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      }, {
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      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/envoyproxy/gateway/security/advisories/GHSA-fcrp-7gc2-93g7"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/envoyproxy/gateway"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-862" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-16T19:14:50Z",
    "nvd_published_at" : null
  }
}