TI-2026-38738 Aliases CVE-2026-53718 GHSA-fcrp-7gc2-93g7

Envoy Gateway custom backendRef cross-namespace ReferenceGrant bypass

LOW 29CWE-862Published 2026-09-14 · Updated 2026-09-15

Key facts

Attack vector: Network
Privileges required: Low
User interaction: None
Attack complexity: High
Impact type: Security bypass
Confidentiality · integrity · availability: High · Low · Low
Fix status: Partial Red Hat: 1 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-862.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00413 35th percentileScored 2026-11-07

Fix Partial gateway (envoyproxy): 1.7.4, 1.8.1github.com/envoyproxy/gateway (Go): 1.8.1, 1.7.4Red Hat: 1 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: No
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
envoyproxy	gateway	before 1.7.4; 1.8.0-rc.0 to before 1.8.1	1.7.4, 1.8.1	Patch available	CNA
—	github.com/envoyproxy/gateway (Go)	1.8.0-rc.0 to before 1.8.1	1.8.1	Patch available	GHSA-fcrp-7gc2-93g7
—	github.com/envoyproxy/gateway (Go)	before 1.7.4	1.7.4	Patch available	GHSA-fcrp-7gc2-93g7

gateway Vendorenvoyproxy Affected before 1.7.4; 1.8.0-rc.0 to before 1.8.1 Fixed in 1.7.4, 1.8.1 Patch available CNA
github.com/envoyproxy/gateway (Go) Vendor— Affected 1.8.0-rc.0 to before 1.8.1 Fixed in 1.8.1 Patch available GHSA-fcrp-7gc2-93g7
github.com/envoyproxy/gateway (Go) Vendor— Affected before 1.7.4 Fixed in 1.7.4 Patch available GHSA-fcrp-7gc2-93g7

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPE	Versions	Role	Vendor
cpe:2.3:a:envoyproxy:gateway::::::::	—	—	envoyproxy

cpe:2.3:a:envoyproxy:gateway:*:*:*:*:*:*:*:* Versions — — ·envoyproxy

Remediation

Fix · CNA gateway (envoyproxy) Fixed in 1.7.4, 1.8.1
Fix · GHSA-fcrp-7gc2-93g7 github.com/envoyproxy/gateway (Go) Fixed in 1.8.1 Advisory →
Fix · GHSA-fcrp-7gc2-93g7 github.com/envoyproxy/gateway (Go) Fixed in 1.7.4 Advisory →

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

Product	Status	Plan or fix
Red Hat Connectivity Link 1	Affected	No fix yet: Fix deferred

Timeline

2026-10-02 Threatist record created from CVE-2026-53718
2026-10-03 Alias added: GHSA-fcrp-7gc2-93g7

References

Other 10

TI-2026-79288 Out-of-bounds write in Google Brotli decoder KEVCVSS 4.0CRITICAL 9.2
TI-2023-23979 The HTTP/2 protocol allows a denial of service (server resource consumption) because… KEVCVSS 3.1HIGH 7.5
TI-2024-20001 HTTP/2: CPU exhaustion due to CONTINUATION frame flood CVSS 3.1HIGH 7.5
TI-2024-18524 HTTP/2: memory exhaustion due to CONTINUATION frame flood CVSS 3.1HIGH 7.5
TI-2023-12215 Envoy client may fake the header `x-envoy-original-path` CVSS 3.1CRITICAL 9.1
TI-2023-18002 Envoy vulnerable to OAuth2 credentials exploit with permanent validity CVSS 3.1CRITICAL 9.8

See all 136 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences