Red Hat ACM: ManagedClusterAddOn annotation overrides governance-policy image, giving cluster-admin exec

Impact

The governance-policy-addon-controller lets the container image for the governance-policy addon be set from an annotation on the namespaced ManagedClusterAddOn resource. Anyone able to annotate that resource can point it at an image they control, and the addon runs with cluster-admin on the managed cluster - so the attacker's code executes with full cluster rights on a cluster they were never granted admin on. In a fleet managed by ACM this is a hop from a delegated, namespace-scoped permission on the hub to total control of a managed GPU cluster, including its workloads, node access and secrets. Red Hat's record does not name a fixed ACM version.

Who can reach it

An authenticated user holding permission to annotate the namespaced ManagedClusterAddOn resource - typically a delegated cluster-onboarding or addon-management role, not a hub administrator.

What to do

Track Red Hat's advisory page for CVE-2026-66793 and Bugzilla 2507538 for the fixed Advanced Cluster Management 2.x build; the record in hand does not state one, so do not plan a version number yet. In the meantime, audit and cut RBAC that grants annotate or patch on ManagedClusterAddOn to anyone who is not already a hub administrator, and reconcile the running governance-policy addon images against your expected registry to confirm none were swapped.

References