Policy bypass for Host Firewall policy due to race condition in Cilium agent

Impact

A race condition in the Cilium agent can cause the agent to ignore labels that should be applied to a node. This could in turn cause CiliumClusterwideNetworkPolicies intended for nodes with the ignored label to not apply, leading to policy bypass.

Patches

This issue was fixed in https://github.com/cilium/cilium/pull/33511.

This issue affects:

• All versions of Cilium before v1.14.14
• Cilium v1.15 between v1.15.0 and v1.15.7 inclusive

This issue has been patched in:

• Cilium v1.14.14
• Cilium v1.15.8

Workarounds

As the underlying issue depends on a race condition, users unable to upgrade can restart the Cilium agent on affected nodes until the affected policies are confirmed to be working as expected.

Acknowledgements

The Cilium community has worked together with members of Google and Isovalent to prepare these mitigations. Special thanks to @skmatti for raising and resolving this issue.

For more information

If you have any questions or comments about this advisory, please reach out on Slack.

If you think you have found a vulnerability affecting Cilium, we strongly encourage you to report it to our security mailing list at [email protected]. This is a private mailing list for the Cilium security team, and your report will be treated as top priority.