CVE-2023-30851

Workarounds

Rewrite HTTP rules for each endpoint separately. For example, if the initial rule looks like:

  egress:
    - toEndpoints:
        - matchLabels:
            k8s:kind: echo
        - matchLabels:
            k8s:kind: example
      toPorts:
        - ports:
            - port: "8080"
              protocol: TCP
          rules:
            http:
              - method: "GET"

It should be rewritten to:

  egress:
    - toEndpoints:
        - matchLabels:
            k8s:kind: echo
      toPorts:
        - ports:
            - port: "8080"
              protocol: TCP
          rules:
            http:
              - method: "GET"
    - toEndpoints:
        - matchLabels:
            k8s:kind: example
      toPorts:
        - ports:
            - port: "8080"
              protocol: TCP
          rules:
            http:
              - method: "GET"

Acknowledgements

The Cilium community has worked together with members of Isovalent to prepare these mitigations. Special thanks to @jrajahalme for investigating and fixing the issue.

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.

This issue only impacts users who:

• Have a HTTP policy that applies to multiple toEndpoints AND
• Have an allow-all rule in place that affects only one of those endpoints

In such cases, a wildcard rule will be appended to the set of HTTP rules, which could cause bypass of HTTP policies.

CVE-2023-30851 has a CVSS score of 5.3 (Medium). The vector is network-reachable, 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 (1.11.16, 1.12.9, 1.13.2); upgrading removes the vulnerable code path.

Kodem intelligence

This issue has been patched in Cilium 1.11.16, 1.12.9, and 1.13.2.

1. What is CVE-2023-30851? CVE-2023-30851 is a medium-severity security vulnerability in github.com/cilium/cilium (go), affecting versions < 1.11.16. It is fixed in 1.11.16, 1.12.9, 1.13.2.
2. How severe is CVE-2023-30851? CVE-2023-30851 has a CVSS score of 5.3 (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-2023-30851? github.com/cilium/cilium (go) versions < 1.11.16 is affected.
4. Is there a fix for CVE-2023-30851? Yes. CVE-2023-30851 is fixed in 1.11.16, 1.12.9, 1.13.2. Upgrade to this version or later.
5. Is CVE-2023-30851 exploitable, and should I be worried? Whether CVE-2023-30851 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-2023-30851 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-2023-30851?
   • Upgrade github.com/cilium/cilium to 1.11.16 or later
   • Upgrade github.com/cilium/cilium to 1.12.9 or later
   • Upgrade github.com/cilium/cilium to 1.13.2 or later