🛡️ CVE-2026-41520 — cilium

🟠 CVSS 8.0 — High ✅ No Known Exploit CWE-200 NVD
8.0
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

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](https://docs.cilium.io/en/stable/security/network/encryption-wireguard/) are affected.

The sensitive data is the WireGuard private key (cilium_wg0.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](https://docs.cilium.io/en/latest/community/community/).

Cilium strongly encourages the reporting of suspected vulnerabilities to the security mailing list at [[email protected]](mailto:[email protected]). This is a private mailing list for the Cilium security team, and the report will be treated as top priority.

How this vulnerability can be exploited

This issue can be reached with local access to the system, attack complexity is low, an attacker needs administrative privileges on the target. No user interaction is required. The scope is changed, meaning a successful attack can affect components beyond the vulnerable one. Rated impact: confidentiality high, integrity high, availability none.

Weakness class

CVE-2026-41520 is classified as CWE-200: Exposure of Sensitive Information. Information that should stay internal is disclosed to someone who is not authorised to see it.

Affected software

CVE-2026-41520 is recorded against 5 packages.

  • cilium
  • cilium-operator
  • github.com/cilium/cilium
  • hubble-relay
  • unknown

Timeline and source

Published on 12 May 2026 and last revised on 25 June 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

github.com (Web)
github.com (Web)
github.com (Web)
github.com (Web)
nvd.nist.gov (Web)

Details

Severity MEDIUM
CVSS Score 8.0
CVSS Vector CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N
CWE CWE-200
Public Exploit ✅ No
Source NVD
Published 2026-05-12
Updated 2026-08-12
Modified 2026-06-25
Fix URL N/A

Affected Packages

Software From version Fixed in
cilium — —
cilium-operator — —
github.com/cilium/cilium — —
hubble-relay — —
unknown — —

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