CVE-2026-10090

Summary

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 Software

VendorProductVersion RangeStatus
Red HatRed Hat Advanced Cluster Management for Kubernetes 2.111787263584 < *unaffected
Red HatRed Hat Advanced Cluster Management for Kubernetes 2.131787263693 < *unaffected
Red HatRed Hat Advanced Cluster Management for Kubernetes 2.141787170830 < *unaffected
Red HatRed Hat Advanced Cluster Management for Kubernetes 2.151787240030 < *unaffected
Red HatRed Hat Advanced Cluster Management for Kubernetes 2.161787242321 < *unaffected
Red HatRed Hat Advanced Cluster Management for Kubernetes 2.171787242108 < *unaffected

Weaknesses

  • CWE-267: Privilege Defined With Unsafe Actions

Workarounds

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.

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: total

References