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CVE-2026-10090: Multicluster-operators-subscription: multicluster-operators-subscription: namespace edit user can deploy cluster-scoped clusterrolebinding and become cluster-admin via application subscription

Description

A flaw was found in the Application Subscription controller (multicluster-operators-subscription) of Red Hat Advanced Cluster Management for Kubernetes (ACM). A user with namespace-scoped "edit" privileges in an ACM hub namespace can create a Channel resource pointing to a Helm repository they control and a Subscription resource referencing it. The app-subscription controller fetches and applies the Helm chart contents with its own elevated authority, without verifying whether the subscription creator holds the "open-cluster-management:subscription-admin" role and without restricting applied resources to the subscription namespace. This allows the attacker to include cluster-scoped resources in the Helm chart, such as a ClusterRoleBinding granting the attacker's ServiceAccount the "cluster-admin" ClusterRole. Successful exploitation results in full cluster-admin privilege escalation. This contradicts the ACM documentation which states that non-subscription-admin users should have resources deployed into the subscription namespace only.

Affected products

How to fix

Upgrade to a fixed version: Red Hat Advanced Cluster Management for Kubernetes 2.11 1787263584; Red Hat Advanced Cluster Management for Kubernetes 2.13 1787263693; Red Hat Advanced Cluster Management for Kubernetes 2.14 1787170830; Red Hat Advanced Cluster Management for Kubernetes 2.15 1787240030; Red Hat Advanced Cluster Management for Kubernetes 2.16 1787242321; Red Hat Advanced Cluster Management for Kubernetes 2.17 1787242108. Check the vendor advisory for mitigations.

References

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