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Fencer Vulns
medium 6.4

CVE-2026-53718 json

Envoy Gateway custom backendRef cross-namespace ReferenceGrant bypass

published 2026-07-16 3 mo ago modified 2026-09-25 45 d ago also BIT-envoy-gateway-2026-53718 , EUVD-2026-78072 , GHSA-fcrp-7gc2-93g7 , GO-2026-6007

cvss
6.4
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 35%
public exploits
0
none known

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.

Patch / fix

  • go github.com/envoyproxy/gateway 1.7.4, 1.8.1
  • bitnami envoy-gateway 1.7.4, 1.8.1
  • envoyproxy gateway 1.7.4, 1.8.1
  • govulncheck-vulndb openSUSE Leap 16.0 0.0.20260723T184607-160000.1.1

opensuse advisories openSUSE-SU-2026:21483-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-53718 updated cvss 6.4

github.com/envoyproxy/gateway: Envoy Gateway: Cross-namespace authorization bypass

  • Red Hat Connectivity Link 1 rhcl-1/rhcl-rhel9-operator, rhcl-1/rhcl-operator-bundle
    affected: workaround, no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
55 d ago

Exploit prediction

0.41% chance of exploitation in the next 30 days, higher than 35% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 6.4 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:L
GitHub 3.1 6.4 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:L
OSV 3.1 6.4 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:L

Affected packages

ecosystem package affected fixed in
go github.com/envoyproxy/gateway
>=1.8.0-rc.0, <1.8.1
<1.7.4
1.8.1
1.7.4
bitnami envoy-gateway
<1.7.4
>=1.8.0, <1.8.1
1.7.4
1.8.1

Affected products

  • envoyproxy gateway

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.