CVE-2023-27593

Workarounds

Kubernetes RBAC should be used to deny users and service accounts exec access to Cilium agent pods.

In cases where a user requires exec access to Cilium agent pods, but should not have access to the underlying node, no workaround is possible.

References

• PR containing resolution

Acknowledgements

The Cilium community has worked together with members of Isovalent and Form3 to prepare these mitigations. Special thanks to Anastasios Koutlis, Daniel Teixeira, and Magdalena Oczadly for their cooperation.

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.

An attacker with access to a Cilium agent pod can write to /opt/cni/bin due to a hostPath mount of that directory in the agent pod. By replacing the CNI binary with their own malicious binary and waiting for the creation of a new pod on the node, the attacker can gain access to the underlying node.

CVE-2023-27593 has a CVSS score of 4.4 (Medium). The vector is requires local access, high 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 (1.11.15, 1.12.8, 1.13.1); upgrading removes the vulnerable code path.

Kodem intelligence

The issue has been fixed and is available on versions >=1.11.15, >=1.12.8, >=1.13.1.

1. What is CVE-2023-27593? CVE-2023-27593 is a medium-severity security vulnerability in github.com/cilium/cilium (go), affecting versions < 1.11.15. It is fixed in 1.11.15, 1.12.8, 1.13.1.
2. How severe is CVE-2023-27593? CVE-2023-27593 has a CVSS score of 4.4 (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-2023-27593? github.com/cilium/cilium (go) versions < 1.11.15 is affected.
4. Is there a fix for CVE-2023-27593? Yes. CVE-2023-27593 is fixed in 1.11.15, 1.12.8, 1.13.1. Upgrade to this version or later.
5. Is CVE-2023-27593 exploitable, and should I be worried? Whether CVE-2023-27593 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-2023-27593 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-2023-27593?
   • Upgrade github.com/cilium/cilium to 1.11.15 or later
   • Upgrade github.com/cilium/cilium to 1.12.8 or later
   • Upgrade github.com/cilium/cilium to 1.13.1 or later