Copyright © 2012 Red Hat, Inc. All rights reserved. Important 2026-08-05T08:35:00 multicluster-operators-subscription: multicluster-operators-subscription: namespace edit user can deploy cluster-scoped ClusterRoleBinding and become cluster-admin via Application Subscription 9.0 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:L CWE-267

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.

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.

The ACM Application Subscription model has been deprecated in newer ACM releases. Red Hat recommends migrating to the GitOps Operator / Argo CD model for application management. See KCS https://access.redhat.com/solutions/7146608 for verification steps to determine if your environment uses the Application Subscription model. Migrate to GitOps/Argo CD application model The vulnerability exists specifically in the ACM Application Subscription controller (multicluster-operators-subscription). Environments that use the GitOps Operator / Argo CD application model and do not use the ACM Application Subscription model are not exposed to this vulnerability. . Red Hat would like to thank Christopher Lusk (North Echo Security Research) for reporting this issue. Remove the RBAC aggregation (immediate, targeted) Delete the ClusterRole that aggregates Application Subscription management permissions into the Kubernetes edit role: oc delete clusterrole open-cluster-management:multicloud-operators-subscription:rbac-aggregate-edit Verification: oc auth can-i create subscriptions.apps.open-cluster-management.io --as=<user> -n <namespace> Expected result after mitigation: no Important notes: This ClusterRole is recreated by the multiclusterhub-operator during reconciliation. Customers must re-apply this mitigation after any ACM operator upgrade, operator pod restart, or MultiClusterHub CR modification until a fixed release is installed. After deletion, users with only the edit or view roles will no longer be able to create or delete Application Subscription, Channel, or related resources. Users who are bound to open-cluster-management:subscription-admin or who have explicit RBAC grants are unaffected. Existing Application Subscriptions continue to function normally. Red Hat Advanced Cluster Management for Kubernetes 2 Affected rhacm2/multicluster-operators-subscription-rhel9 https://www.cve.org/CVERecord?id=CVE-2026-10090 https://nvd.nist.gov/vuln/detail/CVE-2026-10090