CVE-2026-53935

ADVISORY - github

Summary

Impact

Users with the ability to create CiliumLocalRedirectPolicies can specify arbitrary ClusterIPs via addressMatcher, which enables hijacking traffic to Services in any namespace, bypassing the namespace-scoping guarantees enforced by serviceMatcher.

In addition, deleting such a policy can corrupt Cilium's internal service state, causing service translation to stop working entirely for the affected Service.

Patches

This issue affects:

Cilium v1.19.0 to v1.19.3 inclusive (fixed in PR #45584)
Cilium v1.18.2 to v1.18.9 inclusive (fixed in PR #45585)
All versions of Cilium prior to v1.17.16 (fixed in PR #45412)

This issue has been patched in:

Cilium v1.19.4
Cilium v1.18.10
Cilium v1.17.16

Workarounds

There is no workaround to this issue.

Acknowledgements

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

For more information

If there are any questions or comments about this advisory, please reach out on Slack.

To report potential vulnerabilities affecting Cilium, it strongly is encouraged to report them through the security mailing list at security@cilium.io. This is a private mailing list for the Cilium security team, and reports will be treated as a top priority.