CVE-2023-39347

Workarounds

An admission webhook can be used to prevent pod label updates to the k8s:io.kubernetes.pod.namespace and io.cilium.k8s.policy.* keys.

Acknowledgements

The Cilium community has worked together with members of Palantir and Isovalent to prepare these mitigations. Special thanks to @odinuge for reporting this issue and to @nebril for the fix.

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 in Cilium, we strongly encourage you to report it 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.

An attacker with the ability to update pod labels can cause Cilium to apply incorrect network policies.

This issue arises due to the fact that on pod update, Cilium incorrectly uses user-provided pod labels to select the policies which apply to the workload in question.

This can affect:

• Cilium network policies that use the namespace, service account or cluster constructs to restrict traffic
• Cilium clusterwide network policies that use Cilium namespace labels to select the Pod
• Kubernetes network policies

Non-existent construct names can be provided, which bypass all network policies applicable to the construct. For example, providing a pod with a non-existent namespace as the value of the io.kubernetes.pod.namespace label results in none of the namespaced CiliumNetworkPolicies applying to the pod in question.

This attack requires the attacker to have Kubernetes API Server access, as described in the Cilium Threat Model.

CVE-2023-39347 has a CVSS score of 5.4 (Medium). The vector is reachable from an adjacent network, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.13.7, 1.14.2, 1.12.14); upgrading removes the vulnerable code path.

Kodem intelligence

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

1. What is CVE-2023-39347? CVE-2023-39347 is a medium-severity security vulnerability in github.com/cilium/cilium (go), affecting versions >= 1.13.0, <= 1.13.6. It is fixed in 1.13.7, 1.14.2, 1.12.14.
2. How severe is CVE-2023-39347? CVE-2023-39347 has a CVSS score of 5.4 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of github.com/cilium/cilium are affected by CVE-2023-39347? github.com/cilium/cilium (go) versions >= 1.13.0, <= 1.13.6 is affected.
4. Is there a fix for CVE-2023-39347? Yes. CVE-2023-39347 is fixed in 1.13.7, 1.14.2, 1.12.14. Upgrade to this version or later.
5. Is CVE-2023-39347 exploitable, and should I be worried? Whether CVE-2023-39347 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2023-39347 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2023-39347?
   • Upgrade github.com/cilium/cilium to 1.13.7 or later
   • Upgrade github.com/cilium/cilium to 1.14.2 or later
   • Upgrade github.com/cilium/cilium to 1.12.14 or later