Envoy Gateway custom backendRef cross-namespace ReferenceGrant bypass

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-53718
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-14 21:17:13 UTC
Updated2026-09-25 14:10:13 UTC
DescriptionEnvoy 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.

Risk And Classification

Primary CVSS: v3.1 6.4 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:L

EPSS: 0.004130000 probability, percentile 0.330100000 (date 2026-09-27)

Problem Types: CWE-862 | CWE-862 CWE-862: Missing Authorization

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary6.4MEDIUMCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:L
3.1CNADECLARED6.4MEDIUMCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:L

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
Low
Availability
Low

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:L

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Envoyproxy Gateway affected < 1.7.4 Not specified
CNA Envoyproxy Gateway affected >= 1.8.0-rc.0, < 1.8.1 Not specified

References

ReferenceSourceLinkTags
github.com/envoyproxy/gateway/releases/tag/v1.8.1 [email protected] github.com
github.com/envoyproxy/gateway/pull/9173 [email protected] github.com
github.com/envoyproxy/gateway/pull/9172 [email protected] github.com
github.com/envoyproxy/gateway/commit/b4737180c7e597490c6363075c565fa8cf2... [email protected] github.com
github.com/envoyproxy/gateway/releases/tag/v1.7.4 [email protected] github.com
github.com/envoyproxy/gateway/commit/96e2b750868a459ace4b8b68e6a6e4fb015... [email protected] github.com
github.com/envoyproxy/gateway/security/advisories/GHSA-fcrp-7gc2-93g7 [email protected] github.com
github.com/envoyproxy/gateway/commit/5a78db82b7cf4fc5bebbeda2c5095289203... [email protected] github.com
github.com/envoyproxy/gateway/pull/9171 [email protected] github.com
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