CVE-2026-10090

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

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Published Aug 5, 2026 CVSS 3.1 · 9 Critical EPSS < 1% KEV · Not listed
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.

Analysis

AI-generated

Technical impact

A flaw was found in the Application Subscription controller 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 that references it. The controller then fetches and applies the chart contents with its own elevated authority, without checking whether the subscription creator has the open‑cluster‑management:subscription‑admin role and without restricting applied resources to the subscription namespace. This omission allows an attacker to include cluster‑scoped objects in the Helm chart, such as a ClusterRoleBinding that grants the attacker’s ServiceAccount the cluster‑admin ClusterRole. Successful exploitation results in full cluster‑admin privilege escalation. The CVSS score is 9 and the weakness corresponds to CWE‑267.

Affected Systems

The vulnerability affects Red Hat Advanced Cluster Management for Kubernetes version 2 (ACM 2). Exact sub‑version details are not publicly disclosed, but any installation of ACM 2 that still uses the default multicluster‑operators‑subscription controller is impacted.

Risk and Exploitability

With a CVSS score of 9 the flaw is rated critical. The EPSS score is < 1%, indicating a low probability of exploitation, yet the risk remains high due to the lack of a patch and the requirement of only namespace‑scoped edit rights. Attackers can deploy cluster‑scoped resources through a controlled Helm repository, gaining cluster‑admin rights and potentially compromising the entire cluster. This vulnerability is not listed in the CISA KEV catalog. Without an official fix, this risk remains high for all affected ACM 2 deployments.

Remediation

Vendor Workaround

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.

OpenCVE Recommended Actions

  • Delete the ClusterRole open‑cluster‑management:multicloud‑operators‑subscription:rbac‑aggregate‑edit using oc delete clusterrole open-cluster-management:multicloud-operators-subscription:rbac-aggregate-edit.
  • Restrict the namespace‑scoped edit role to only subscription‑admin users so that non‑admin users cannot create Channel or Subscription resources.
  • Deploy an admission controller or policy that blocks Subscription or Channel resources containing cluster‑scoped objects, ensuring all applied resources remain within the subscription namespace.
  • Monitor Red Hat advisories for an official patch and apply it promptly when available.

Generated by OpenCVE AI on August 13, 2026 at 10:50 UTC.

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
CPEs cpe:/a:redhat:acm:2.11::el9
cpe:/a:redhat:acm:2.14::el9
cpe:/a:redhat:acm:2.16::el9
References
Type Values Removed Values Added
CPEs cpe:/a:redhat:acm:2 cpe:/a:redhat:acm:2.13::el9
cpe:/a:redhat:acm:2.15::el9
cpe:/a:redhat:acm:2.17::el9
References
Type Values Removed Values Added
Metrics cvssV3_1

{'score': 9.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H'}

 cvssV3_1

{'score': 9, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:L'}
Type Values Removed Values Added
Metrics cvssV3_1

{'score': 9.9, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H'}

 cvssV3_1

{'score': 9.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H'}
Type Values Removed Values Added
First Time appeared Redhat advanced Cluster Management For Kubernetes
Vendors & Products Redhat advanced Cluster Management For Kubernetes
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}
Type Values Removed Values Added
References
Metrics threat_severity

None

 threat_severity

Important
Type Values Removed Values Added
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.
Title Multicluster-operators-subscription: multicluster-operators-subscription: namespace edit user can deploy cluster-scoped clusterrolebinding and become cluster-admin via application subscription
First Time appeared Redhat
Redhat acm
Weaknesses CWE-267
CPEs cpe:/a:redhat:acm:2
Vendors & Products Redhat
Redhat acm
References
Metrics cvssV3_1

{'score': 9.9, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H'}
Earlier changes (3)
Weaknesses
  • CWE-267

    Privilege Defined With Unsafe Actions

Sources

Status
PUBLISHED
Assigner
redhat
Published
Updated
Sep 8, 2026, 1:09 PM
Reserved
May 29, 2026, 1:35 PM

View source JSON

Updated
Aug 5, 2026, 1:49 PM

JSON

Status
Awaiting Analysis
Published
Aug 5, 2026, 9:18 AM
Modified
Oct 23, 2026, 9:10 PM

View source JSON

Severity
Important
Public date
Aug 5, 2026, 8:35 AM

View source Bugzilla JSON

Updated
Aug 13, 2026, 11:00 AM

JSON