Cilium node based network policies may incorrectly allow workload traffic

Impact

Node based network policies (fromNodes and toNodes) will incorrectly permit traffic to/from non-node endpoints that share the labels specified in fromNodes and toNodes sections of network policies. Node based network policy is disabled by default in Cilium.

Patches

This issue was fixed by https://github.com/cilium/cilium/pull/36657.

This issue affects:

• Cilium v1.16 between v1.16.0 and v1.16.7 inclusive
• Cilium v1.17 between v1.17.0 and v1.17.1 inclusive

This issue is fixed in:

• Cilium v1.16.8
• Cilium v1.17.2

Workarounds

Users can work around this issue by ensuring that the labels used in fromNodes and toNodes fields are used exclusively by nodes and not by other endpoints.

Acknowledgements

The Cilium community has worked together with members of Isovalent to prepare these mitigations. Special thanks to @oblazek for reporting and fixing this issue.

For more information

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. Please also address any comments or questions on this advisory to the same mailing list.