Summary
Envoy Gateway custom backendRef cross-namespace ReferenceGrant bypass
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.
The application does not perform an authorization check before performing a sensitive operation. Typical impact: unauthorized access to restricted functionality or data.
CVE-2026-53718 has a CVSS score of 6.4 (Medium). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.8.1, 1.7.4); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2026-53718? CVE-2026-53718 is a medium-severity missing authorization vulnerability in github.com/envoyproxy/gateway (go), affecting versions >= 1.8.0-rc.0, < 1.8.1. It is fixed in 1.8.1, 1.7.4. The application does not perform an authorization check before performing a sensitive operation.
- How severe is CVE-2026-53718? CVE-2026-53718 has a CVSS score of 6.4 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of github.com/envoyproxy/gateway are affected by CVE-2026-53718? github.com/envoyproxy/gateway (go) versions >= 1.8.0-rc.0, < 1.8.1 is affected.
- Is there a fix for CVE-2026-53718? Yes. CVE-2026-53718 is fixed in 1.8.1, 1.7.4. Upgrade to this version or later.
- Is CVE-2026-53718 exploitable, and should I be worried? Whether CVE-2026-53718 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-53718 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-53718?
- Upgrade
github.com/envoyproxy/gatewayto 1.8.1 or later - Upgrade
github.com/envoyproxy/gatewayto 1.7.4 or later
- Upgrade