What is the CVSS score of EUVD-2026-44773?

EUVD-2026-44773 has a CVSS 3.1 base score of 8.9 (High). CVSS vector: CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:L. EPSS exploitation probability: 0.2%.

Which versions of Cilium are affected by EUVD-2026-44773?

Cilium's Gateway API implementation (versions prior to 1.17.17, 1.18.11, and 1.19.5) contains a cross-namespace authorization bypass allowing users with HTTPRoute creation privileges to access and…. A patch is available.

How to fix or mitigate EUVD-2026-44773?

Within 24 hours, audit all Kubernetes clusters running Cilium to determine which have Gateway API explicitly enabled and document current Cilium version tracks; flag any multi-tenant clusters as highest priority. Within 7 days, evaluate and test Cilium patch versions 1.17.17, 1.18.11, or 1.19.5 (matching your current track) in a staging environment, verifying that ReferenceGrant cross-namespace access controls are properly enforced post-patch. Within 30 days, deploy patched Cilium versions to all production clusters with Gateway API enabled, prioritizing multi-tenant environments.

Cilium EUVD-2026-44773

| CVE-2026-56742 HIGH

Missing Authorization (CWE-862)

2026-07-15 GitHub_M

Authentication Bypass Cilium

8.9

CVSS 3.1 · NVD

Severity by source

Vendor (GitHub_M) PRIMARY

MEDIUM

qualitative

NVD

8.9 HIGH

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

vuln.today AI

8.5 HIGH

Exploited via the Kubernetes API by an authenticated tenant with namespaced route RBAC (AV:N/PR:L); crosses the namespace boundary (S:C); mirroring primarily exfiltrates traffic (C:H) with no data modification (I:N) and possible load amplification (A:L).

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

4.0 AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:L/SC:N/SI:N/SA:N

Primary rating from Vendor (GitHub_M).

CVSS VectorNVD

Attack Vector

Adjacent

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Changed

Confidentiality

High

Integrity

High

Availability

Low

Lifecycle Timeline

Analysis Updated

Jul 17, 2026 - 17:58 vuln.today

v2 (cvss_changed)

Re-analysis Queued

Jul 17, 2026 - 17:52 vuln.today

cvss_changed

Severity Changed

Jul 17, 2026 - 17:52 NVD

MEDIUM HIGH

CVSS changed

Jul 17, 2026 - 17:52 NVD

5.9 (MEDIUM) 8.9 (HIGH)

Patch available

Jul 15, 2026 - 21:18 EUVD

Source Code Evidence Fetched

Jul 15, 2026 - 20:01 vuln.today

Analysis Generated

Jul 15, 2026 - 20:01 vuln.today

DescriptionNVD

Cilium is a networking, observability, and security solution. Prior to 1.17.17, 1.18.11, and 1.19.5, Cilium clusters using Gateway API allow users with permissions to create or update namespaced HTTPRoutes to mirror HTTP traffic to any Service in any namespace, bypassing the ReferenceGrant authorization mechanism. Gateway API functionality is disabled by default. This issue is fixed in versions 1.17.17, 1.18.11, and 1.19.5.

AnalysisAI

Cross-namespace authorization bypass in Cilium's Gateway API implementation (versions prior to 1.17.17, 1.18.11, and 1.19.5) lets any user holding namespaced permission to create or update HTTPRoutes (and GRPCRoutes) attach a RequestMirror filter that copies HTTP/gRPC traffic to any Service in any namespace, silently defeating the Kubernetes Gateway API ReferenceGrant control that is supposed to gate cross-namespace backend references. This is a CWE-862 missing-authorization flaw (CVSS 8.9) that enables tenant-boundary violation and traffic exfiltration in multi-tenant clusters. There is no public exploit identified at time of analysis, it is not in CISA KEV, and EPSS is low (0.20%); Gateway API is also disabled by default, so exposure is limited to clusters that have explicitly enabled it.

Technical ContextAI

Cilium is a CNCF eBPF-based CNI providing networking, observability, and security for Kubernetes. This issue lives in Cilium's operator-side translation of Kubernetes Gateway API resources into its datapath model (operator/pkg/model/ingestion/gateway.go). In Gateway API, a RequestMirror filter on an HTTPRoute/GRPCRoute duplicates live request traffic to a named backend Service; when that backend lives in a different namespace, the spec requires an explicit ReferenceGrant in the target namespace to authorize the reference. Cilium correctly enforced ReferenceGrant for normal BackendRefs but failed to run the same check for the mirror filter's BackendRef - the fix adds an IsBackendReferenceAllowed(grants) guard (and a nil-filter safety check) for both extractRoutes (HTTPRoute) and toGRPCRoutes (GRPCRoute) paths. The root cause (CWE-862, Missing Authorization) is an incomplete authorization check: an enforcement mechanism existed for one reference path but was not applied to a functionally equivalent one.

RemediationAI

Vendor-released patch: upgrade Cilium to 1.17.17, 1.18.11, or 1.19.5 (release tags https://github.com/cilium/cilium/releases/tag/v1.17.17, /v1.18.11, /v1.19.5); the fix is implemented in commits 7422068, e0b1cef, f23929c, and fd47963, which add the missing ReferenceGrant enforcement to mirror BackendRefs. If you cannot patch immediately, the most effective compensating control is to disable the Gateway API feature in Cilium if it is not required (this removes the attack surface entirely but also removes Gateway API routing/mirroring functionality); alternatively, tighten Kubernetes RBAC so that untrusted or multi-tenant users cannot create or update HTTPRoute/GRPCRoute objects (trade-off: legitimate self-service route management for those tenants is lost), and audit existing HTTPRoutes/GRPCRoutes for RequestMirror filters whose BackendRef points to a Service in another namespace without a corresponding ReferenceGrant. Follow the vendor advisory GHSA-w7c2-w76w-5hmj for authoritative guidance.