CVE-2026-41520: Cillium exposes sensitive information included in the cilium-bugtool debug archive
Impact The output of cilium-bugtool can contain sensitive data when the tool is run against Cilium deployments with WireGuard encryption enabled.
Users of WireGuard Transparent Encryption are affected. The sensitive data is the WireGuard private key (ciliumwg0.key) used for node-to-node encrypted communication
cilium-bugtool is a debugging tool that is typically invoked manually and does not run during the normal operation of a Cilium cluster. It is also invoked when gathering sysdumps using the Cilium CLI's cilium sysdump command.
Patches This issue affects:
- Cilium v1.19 between v1.19.0 and v1.19.2 inclusive - Cilium v1.18 between v1.18.0 and v1.18.8 inclusive - All versions of Cilium prior to v1.17.15
This issue has been patched in:
- Cilium v1.19.3 - Cilium v1.18.9 - Cilium v1.17.15
Workarounds There is no workaround to this issue.
Users who have previously shared bugtool or sysdump archives from WireGuard-enabled nodes should rotate the WireGuard keys on the affected nodes. This can be done by deleting the key file and restarting the Cilium agent, which will generate a new key pair.
Acknowledgements
The Cilium community has worked together with members of Isovalent to prepare these mitigations. Cillium extends special thanks to @kodareef5 for reporting the issue and @tklauser for their work on triaging and remediating this issue.
For more information
If there are any questions or comments about this advisory, please reach out on Slack.
Cilium strongly encourages the reporting of suspected vulnerabilities to the security mailing list at security@cilium.io. This is a private mailing list for the Cilium security team, and the report will be treated as top priority.
Other sources
Cilium is a networking, observability, and security solution with an eBPF-based dataplane. Prior to versions 1.17.15, 1.18.9, and 1.19.3, the output of cilium-bugtool can contain sensitive data when the tool is run against Cilium deployments with WireGuard encryption enabled. This issue has been patched in versions 1.17.15, 1.18.9, and 1.19.3.
— MITRE
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2026-41520?
The severity of CVE-2026-41520 is classified as a medium risk due to the potential exposure of sensitive data.
How do I fix CVE-2026-41520?
To fix CVE-2026-41520, upgrade to Cilium versions 1.19.3, 1.18.9, or any version higher than 1.17.15.
Who is affected by CVE-2026-41520?
Users of Cilium deployments that have WireGuard encryption enabled are affected by CVE-2026-41520.
What data is exposed in CVE-2026-41520?
CVE-2026-41520 may expose sensitive information when running the cilium-bugtool on affected systems.
When was CVE-2026-41520 disclosed?
CVE-2026-41520 was disclosed as part of a security advisory from the maintainers of Cilium.