Cilium L7 proxy may bypass Kubernetes NetworkPolicy for same-node traffic
Key facts
- Attack vector
- Adjacent network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- Low · Low · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-284.
Summary
Cilium is a networking, observability, and security solution with an eBPF-based dataplane. Prior to versions 1.17.14, 1.18.8, and 1.19.2, Ingress Network Policies are not enforced for traffic from pods to L7 Services (Envoy, GAMMA) with a local backend on the same node, when Per-Endpoint Routing is enabled and BPF Host Routing is disabled. Per-Endpoint Routing is disabled by default, but is automatically enabled in deployments using cloud IPAM, including Cilium ENI on EKS (`eni.enabled`), AlibabaCloud ENI (`alibabacloud.enabled`), Azure IPAM (`azure.enabled`, but not AKS BYOCNI), and some GKE deployments (`gke.enabled`; managed offerings such as GKE Dataplane V2 may use different defaults). It is typically not enabled in tunneled deployments, and chaining deployments are not affected. In practice, Amazon EKS with Cilium ENI mode is likely the most common affected environment. Versions 1.17.14, 1.18.8, and 1.19.2 contain a patch. There is currently no officially verified or comprehensive workaround for this issue. The only option would be to disable per-endpoint routes, but this will likely cause disruptions to ongoing connections, and potential conflicts if running in cloud providers.
Why it matters now
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 |
|---|---|---|---|---|---|
| cilium | cilium | before 1.17.14; 1.18.0 to before 1.18.8; 1.19.0 to before 1.19.2 | 1.17.14, 1.18.8, 1.19.2 | Patch available | CNA |
| — | github.com/cilium/cilium (Go) | before 1.17.14 | 1.17.14 | Patch available | GHSA-hxv8-4j4r-cqgv |
| — | github.com/cilium/cilium (Go) | 1.18.0 to before 1.18.8 | 1.18.8 | Patch available | GHSA-hxv8-4j4r-cqgv |
| — | github.com/cilium/cilium (Go) | 1.19.0 to before 1.19.2 | 1.19.2 | Patch available | GHSA-hxv8-4j4r-cqgv |
- cilium Vendorcilium Affected before 1.17.14; 1.18.0 to before 1.18.8; 1.19.0 to before 1.19.2 Fixed in 1.17.14, 1.18.8, 1.19.2 Patch available CNA
- github.com/cilium/cilium (Go) Vendor— Affected before 1.17.14 Fixed in 1.17.14 Patch available GHSA-hxv8-4j4r-cqgv
- github.com/cilium/cilium (Go) Vendor— Affected 1.18.0 to before 1.18.8 Fixed in 1.18.8 Patch available GHSA-hxv8-4j4r-cqgv
- github.com/cilium/cilium (Go) Vendor— Affected 1.19.0 to before 1.19.2 Fixed in 1.19.2 Patch available GHSA-hxv8-4j4r-cqgv
Remediation
- Fix · CNA cilium (cilium) Fixed in 1.17.14, 1.18.8, 1.19.2
- Fix · GHSA-hxv8-4j4r-cqgv github.com/cilium/cilium (Go) Fixed in 1.17.14 Advisory →
- Fix · GHSA-hxv8-4j4r-cqgv github.com/cilium/cilium (Go) Fixed in 1.18.8 Advisory →
- Fix · GHSA-hxv8-4j4r-cqgv github.com/cilium/cilium (Go) Fixed in 1.19.2 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2026-33726
- 2026-10-03 Alias added: GHSA-hxv8-4j4r-cqgv
References
Patch 2
Other 5
- https://docs.cilium.io/en/stable/network/concepts/routing/#routing
- https://docs.cilium.io/en/stable/network/kubernetes/policy/#network-policy
- https://docs.cilium.io/en/stable/network/servicemesh/l7-traffic-management
- https://docs.cilium.io/en/stable/operations/performance/tuning/#ebpf-host-routing
- https://github.com/cilium/cilium
More Cilium vulnerabilities
- TI-2024-32092 CIDR deny policies may not take effect when a more narrow CIDR allow is present CVSS 3.1HIGH 8.7
- TI-2023-12305 Cilium eBPF filters may be temporarily removed during agent restart CVSS 3.1CRITICAL 9.8
- TI-2023-20486 Cilium NetworkPolicy bypass via pod labels CVSS 3.1CRITICAL 9.0
- TI-2022-11721 Incorrect Default Permissions in Cilium CVSS 3.1HIGH 8.8
- TI-2026-36600 Cilium: Sensitive information disclosure and cluster disruption via local Envoy admin socket access CVSS 3.1CRITICAL 9.2
- TI-2026-40915 Cilium: Namespaced HTTPRoutes can redirect traffic to other namespaces CVSS 3.1HIGH 8.9
Sources
- CVE-2026-33726 · CVE Program
- CVE-2026-33726 · NVD
- FIRST EPSS
- GHSA-hxv8-4j4r-cqgv · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences