Constallation has pods exposed to peers in VPC

Summary

### Impact

Cilium allows outside actors (`world` entity) to directly access pods with their internal pod IP, even if they are not exposed explicitly (e.g. via `LoadBalancer`). A pod that does not authenticate clients and that does not exclude `world` traffic via network policy may leak sensitive data to an attacker _inside the cloud VPC_.

### Patches

The issue has been patched in [v2.16.3](https://github.com/edgelesssys/constellation/releases/tag/v2.16.3).

### Workarounds

This network policy excludes all `world` traffic. It mitigates the problem, but will also block all desired external traffic. If vulnerable pods are known, a policy can be crafted to only firewall those instead (see also https://docs.cilium.io/en/stable/security/policy/language/#access-to-from-outside-cluster).

```yaml apiVersion: "cilium.io/v2" kind: CiliumClusterwideNetworkPolicy metadata: name: "from-world-to-role-public" spec: endpointSelector: matchLabels: {} # role: public ingressDeny: - fromEntities: - world ```

### References

The tracking bug for a Cilium-side fix is https://github.com/cilium/cilium/issues/25626.