CVE-2026-56742 cilium CVE debrief

Who should care

Users of Cilium clusters with Gateway API enabled, particularly those with permissions to create or update namespaced HTTPRoutes, should review their configurations and ensure that proper authorization mechanisms are in place.

Technical summary

Prior to Cilium versions 1.17.17, 1.18.11, and 1.19.5, Cilium clusters using Gateway API allow users with permissions to create or update namespaced HTTPRoutes to mirror HTTP traffic to any Service in any namespace, bypassing the ReferenceGrant authorization mechanism. This issue has a medium CVSS score of 5.9. Gateway API functionality is disabled by default. Users should review and restrict permissions for creating or updating namespaced HTTPRoutes.

Defensive priority

Medium priority due to the medium CVSS score of 5.9 and the potential for traffic mirroring across namespaces.

Recommended defensive actions

• Update Cilium to version 1.17.17, 1.18.11, or 1.19.5
• Review and restrict permissions for creating or updating namespaced HTTPRoutes
• Monitor traffic and audit logs for potential exploitation attempts
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record was published on 2026-07-15T20:17:51.850Z and was last modified on 2026-07-16T14:16:55.273Z. The NVD entry is currently Undergoing Analysis. This information is based on the CVE record and NVD entry. Further verification is recommended.

Official resources