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CVE-2026-56742BIT-cilium-2026-56742BIT-cilium-operator-2026-56742BIT-hubble-relay-2026-56742GHSA-w7c2-w76w-5hmjGO-2026-6596

github.com/cilium/cilium: Cilium: Namespaced HTTPRoutes can redirect traffic to other namespaces

cilium github.com/cilium/ciliumgoLibraries & packages
Open in ThreatlineRecord JSON
CVSS
5.9Medium
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.17%Chance of exploitation activity in the next 30 days, higher than 6% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in1.17.17Also 1.18.11, 1.19.5GitHub
Published15 Jul 2026Updated 1 Oct 2026CVE List

What fixes it

  • 1.17.17github.com/cilium/cilium, goGitHubgo get github.com/cilium/cilium@v1.17.17
  • 1.18.11github.com/cilium/ciliumCilium, goGitHubgo get github.com/cilium/ciliumCilium@v1.18.11
  • 1.19.5github.com/cilium/cilium, goGitHubgo get github.com/cilium/cilium@v1.19.5
  • 1.17.17github.com/cilium/cilium, GoOSVgo get github.com/cilium/cilium@v1.17.17
  • 1.18.11github.com/cilium/ciliumCilium, GoOSVgo get github.com/cilium/ciliumCilium@v1.18.11
  • 1.19.5github.com/cilium/cilium, GoOSVgo get github.com/cilium/cilium@v1.19.5

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

Description

Impact

In Cilium clusters using Gateway API, users with permissions to create or update namespaced HTTPRoutes can mirror HTTP traffic to any Service in any namespace, bypassing the ReferenceGrant authorization mechanism.

Gateway API functionality is disabled by default.

Patches

This issue affects:

  • Cilium v1.19 from v1.19.0 to v1.19.4 inclusive
  • Cilium v1.18 from v1.18.0 to v1.18.10 inclusive
  • All versions of Cilium before v1.17.17

This issue is patched in:

  • Cilium v1.19.5
  • Cilium v1.18.11
  • Cilium v1.17.17

Workarounds

There is no workaround to this issue. Users of this feature who are unable to upgrade can mitigate the risk by ensuring that RBAC permissions to create HTTPRoute objects are only granted to cluster admins.

Acknowledgements

The Cilium community has worked together with members of Isovalent to prepare these mitigations. Special thanks to @galanko for reporting the issue and @mhofstetter for their work on triaging and remediating this issue.

For more information

If you have any questions or comments about this advisory, please reach out on Slack.

If you think you have found a vulnerability affecting Cilium, we strongly encourage you to report it to our security mailing list at [security@cilium.io](mailto:security@cilium.io). This is a private mailing list for the Cilium security team, and your report will be treated as top priority.

Text from GitHub Advisory Database

Affected versions 9

  • github.com/cilium/cilium, go< 1.17.17GitHub
  • github.com/cilium/ciliumCilium, go>= 1.18.0, < 1.18.11GitHub
  • github.com/cilium/cilium, go>= 1.19.0, < 1.19.5GitHub
  • ciliumaffected: < 1.17.17CVE List
  • ciliumaffected: >= 1.18.0, < 1.18.11CVE List
  • ciliumaffected: >= 1.19.0, < 1.19.5CVE List
  • github.com/cilium/cilium, Gofrom first release, fixed in 1.17.17OSV
  • github.com/cilium/ciliumCilium, Gofrom 1.18.0, fixed in 1.18.11OSV
  • github.com/cilium/cilium, Gofrom 1.19.0, fixed in 1.19.5OSV

References 10