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Cluster-admin privilege escalation in Red Hat ACM Application Subscription controller
CVE-2026-10090 is a privilege escalation vulnerability in the Application Subscription controller (multicluster-operators-subscription) of Red Hat Advanced Cluster Management for Kubernetes 2. A user with namespace-scoped edit privileges in an ACM hub namespace can create a Channel referencing an attacker-controlled Helm repository and a Subscription referencing that Channel. The controller applies the Helm chart using its own elevated authority without checking whether the creator holds the open-cluster-management:subscription-admin role or confining deployed resources to the subscription namespace. A malicious chart can consequently deploy a cluster-scoped ClusterRoleBinding granting the attacker's ServiceAccount the cluster-admin role, bypassing namespace isolation and providing full cluster administrative privileges.
What it means and what to do now: patch path, interim mitigations, and the assume-compromise checklist.
What an attacker gets, and what they’ve been doing with it.
Successful exploitation elevates namespace-scoped edit access to full administrative control of the ACM hub's Kubernetes cluster and breaks tenant isolation. This can enable access to secrets and data across namespaces, modification of workloads and access controls, and deployment of privileged workloads. Compromise of the hub could also enable pivoting into registered managed clusters; that downstream outcome is potential rather than established for every deployment.
If you can’t patch tonight, do this now.
Restrict namespace-scoped edit permissions in ACM hub namespaces to trusted users and prevent untrusted users from creating or modifying Channel and Subscription resources. Consider admission-control policies that deny cluster-scoped resources, particularly ClusterRoleBinding objects, originating from untrusted subscription-managed Helm content. Audit existing edit permissions and monitor Channel and Subscription changes for unauthorized repository references. These are interim compensating controls; Red Hat stated that no dedicated mitigation met its product-security criteria.
Patch, then assume compromise.
Apply the Red Hat security update addressing CVE-2026-10090 for the affected Application Subscription controller when available. Fixed-version information is inconsistent: ACM 2.9.2 and 2.8.5 are reported as fixed in one account, while other entries state that no errata had been issued or provide no fixed versions. Confirm the applicable corrected release and package through Red Hat's current security guidance before relying on those version claims.
No public exploits tracked yet. Mallory keeps watching.
20 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.