CVE-2026-10090: Red Hat ACM Privilege Escalation Flaw Grants Cluster-Admin, Rated CVSS 9.9
Do Son 
TL;DR
Red Hat disclosed a critical privilege escalation flaw in Advanced Cluster Management (ACM) for Kubernetes. Tracked as CVE-2026-10090, it scores 9.9 on CVSS. A user with only namespace edit rights can seize full cluster-admin control.
- CVE: CVE-2026-10090
- CVSS: 9.9 (Critical · CVSSv3)
- Product: Red Hat Advanced Cluster Management for Kubernetes 2
- Impact: Multicluster-operators-subscription: multicluster-operators-subscription: namespace edit user can deploy cluster-scoped clusterrolebinding and become cluster-admin via application subscription
- Status: No confirmed exploitation yet
- EPSS: 0.2% (30-day)
- Action: See vendor advisory
Why it matters
ACM manages fleets of Kubernetes clusters from a central hub. Cluster-admin is the top level of access. Therefore this Red Hat ACM privilege escalation turns a low-privileged account into total control.
How the attack works
The flaw sits in the Application Subscription controller. A user with namespace-scoped “edit” rights creates a Channel pointing to a Helm repository they own. They then add a Subscription that references it.
The controller fetches and applies the Helm chart using its own elevated authority. Crucially, it never checks for the “subscription-admin” role. It also fails to confine applied resources to the subscription namespace.
As a result, the attacker can smuggle in cluster-scoped resources. A ClusterRoleBinding can bind their ServiceAccount to cluster-admin. The Red Hat security advisory for CVE-2026-10090 notes this contradicts documented behavior for non-admin users.
Exploitation status
Red Hat has not confirmed any in-the-wild exploitation. No public proof-of-concept has been reported.
Affected versions
The flaw affects Red Hat Advanced Cluster Management for Kubernetes. Check the linked advisory for the exact fixed builds for your release.
Patch and mitigation
Apply Red Hat’s updates as soon as they are available. In the meantime, limit who holds namespace “edit” rights on ACM hub namespaces. Also audit existing Channel and Subscription resources for untrusted Helm sources.
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