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BIT-cilium-2026-26963 — Cilium may not enforce host firewall policies when Native Routing, WireGuard and Node Encryption are enabled

Affected: Bitnami: cilium

Cilium is a networking, observability, and security solution with an eBPF-based dataplane. Versions 1.18.0 through 1.18.5 will incorrectly permit traffic from Pods on other nodes when Native Routing, WireGuard and Node Encryption are enabled. This issue has been fixed in version 1.18.6.

EUVD-2026-268929

fkie_cve-2026-26963

GHSA-5r23-prx4-mqg3 — Cilium may not enforce host firewall policies when Native Routing, WireGuard and Node Encryption are enabled

Affected: Go: github.com/cilium/cilium

### Impact

[Host Policies](https://docs.cilium.io/en/stable/security/policy/language/#host-policies) will incorrectly permit traffic from Pods on other nodes when all of the following configurations are enabled: * [Native Routing](https://docs.cilium.io/en/stable/network/concepts/routing/#native-routing) * [WireGuard](https://docs.cilium.io/en/stable/security/policy/language/#host-policies) * [Node Encryption](https://docs.cilium.io/en/stable/security/network/encryption-wireguard/#node-to-node-encryption-beta) (beta)

These options are disabled by default in Cilium.

### Patches

This issue was fixed by #42892.

This issue affects:

* Cilium v1.18 between v1.18.0 and v1.18.5 inclusive

This issue is fixed in:

* Cilium v1.18.6

### Workarounds

There is currently no officially verified or comprehensive workaround for this issue. The following procedure has been validated strictly within a local 'Kind' environment and has not undergone exhaustive testing across diverse production architectures. Proceed with caution.

To mitigate the identified traffic bypass, ensure all ingress traffic from the `cilium_wg0` interface is explicitly routed to `cilium_host` for policy enforcement. This ensures that host-level security policies are applied to decrypted WireGuard traffic. Execute the following configuration on each CiliumNode:

```bash # IPv4 Traffic ip rule add iif cilium_wg0 table 300 ip route add default dev cilium_host table 300

# IPv6 Traffic ip -6 rule add iif cilium_wg0 t…

UBUNTU-CVE-2026-26963

Affected: Ubuntu:22.04:LTS: golang-github-cilium-ebpf, Ubuntu:24.04:LTS: golang-github-cilium-ebpf, Ubuntu:25.10: golang-github-cilium-ebpf, Ubuntu:26.04:LTS: golang-github-cilium-ebpf