East-west traffic not subject to egress policy enforcement for requests via Gateway API load balancers

Vulnerability Description

Cilium is a networking, observability, and security solution with an eBPF-based dataplane. For Cilium users who use Gateway API for Ingress for some services and use LB-IPAM or BGP for LB Service implementation and use network policies to block egress traffic from workloads in a namespace to workloads in other namespaces, egress traffic from workloads covered by such network policies to LoadBalancers configured by `Gateway` resources will incorrectly be allowed. LoadBalancer resources not deployed via a Gateway API configuration are not affected by this issue. This issue affects: Cilium v1.15 between v1.15.0 and v1.15.14 inclusive, v1.16 between v1.16.0 and v1.16.7 inclusive, and v1.17 between v1.17.0 and v1.17.1 inclusive. This issue is fixed in Cilium v1.15.15, v1.16.8, and v1.17.2. A Clusterwide Cilium Network Policy can be used to work around this issue for users who are unable to upgrade.

References

• https://github.com/cilium/cilium/security/advisories/GHSA-24qp-4xx8-3jvj
• https://github.com/cilium/proxy/pull/1172
• https://docs.cilium.io/en/stable/network/lb-ipam