CVE-2026-91182

A flaw was found in open-cluster-management. An agent communicating via the gRPC broker can bypass authorization by manipulating the `ce-clustername` cloud event header attribute, which is used for authorization, independently of the actual event payload. This allows a registered managed cluster to gain unauthorized access, enabling it to move itself into other tenants' ManagedClusterSets and overwrite other clusters' ManagedCluster objects in the hub. The primary consequence is a breach of isolation between managed clusters, leading to unauthorized modification of cluster resources. This can lead to unauthorized receipt of newly delivered tenant workloads, policies, and secrets via Placement decisions. Additionally, an attacker can arbitrarily overwrite other clusters' ManagedCluster objects on the hub or perform unauthorized writes inside another cluster's dedicated hub namespace, such as forging Lease liveness heartbeats to manipulate availability status.