Specific Cilium configurations vulnerable to DoS via Kubernetes annotations

Impact

In Cilium clusters where Cilium’s Layer 7 proxy has been disabled, creating workloads with

• policy.cilium.io/proxy-visibility annotations (in Cilium >= v1.13)
• io.cilium.proxy-visibility annotations (in Cilium <= v1.12)

causes the Cilium agent to segfault on the node to which the workload is assigned.

Existing traffic on the affected node will continue to flow, but the Cilium agent on the node will not able to process changes to workloads running on the node. This will also prevent workloads from being able to start on the affected node. The denial of service will be limited to the node on which the workload is scheduled, however an attacker may be able to schedule workloads on the node of their choosing, which could lead to targeted attacks.

Patches

Pull request with fix

This issue affects:

Cilium <= v1.14.1
Cilium <= v1.13.6
Cilium <= v1.12.13

This issue has been resolved in:

Cilium v1.14.2
Cilium v1.13.7
Cilium v1.12.14

Workarounds

Users can avoid this denial of service attack by enabling the Layer 7 proxy.

For more information

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

As usual, if you think you found a related vulnerability, we strongly encourage you to report security vulnerabilities to our private security mailing list: [email protected] - first, before disclosing them in any public forums. This is a private mailing list where only members of the Cilium internal security team are subscribed to, and is treated as top priority.