GPUStack: authenticated users can reach Kubernetes clusters with worker credentials

GPUStack is an open-source GPU cluster manager for AI model serving and GPU instance provisioning. From 2.2.0 until 2.2.2, cluster_apiserver_proxy forwarded an authenticated non-administrator's requests to a selected Kubernetes cluster without a resource-level authorization check. The proxy used a reachable worker's Kubernetes ServiceAccount credentials, so the caller could read sensitive resources, create or modify workloads, or delete resources according to that ServiceAccount's permissions. Exploitation required a Kubernetes-provider cluster with a reachable worker, and attacker-controlled workloads could result in code execution in the target cluster. This issue is fixed in version 2.2.2.