Cilium’s L7 proxy can allow traffic from a pod to a locally back‑ended L7 Service to skip enforced ingress NetworkPolicies when Per‑Endpoint Routing is enabled and BPF Host Routing is disabled. This creates an unauthorized data path between the pod and the service, enabling an attacker to send traffic that normally would be denied by cluster policy, potentially compromising confidentiality and integrity. The flaw stems from improper access control and a privilege‑check bypass.

The vulnerability affects Cilium versions prior to 1.17.14, 1.18.8, and 1.19.2. It is relevant for deployments that use cloud IPAM, including Cilium ENI on Amazon EKS, AlibabaCloud ENI, Azure IPAM (except AKS BYOCNI), and certain GKE setups. Typical affected environments are EKS with Cilium ENI mode; tunneled or chaining deployments and GKE Dataplane V2 managed offerings are not impacted.

The CVSS score is 5.4 and the EPSS score is below 1 %, indicating moderate severity and low expected exploitation likelihood. The issue is not listed in CISA’s KEV catalog. The attack vector relies on local‑node pod traffic—an attacker needs a pod on the same node as the target service to exploit the bypass. Updating to the patched version mitigates the flaw, while disabling Per‑Endpoint Routing can act as a temporary workaround at the cost of potential connection disruptions.