KubeSphere: SSRF via Unvalidated Cluster CRD Connection Endpoint in Cluster Reconciliation

KubeSphere's cluster-controller reconciliation (pkg/utils/clusterclient/clusterclient.go, addCluster) processes every Cluster custom resource's connection configuration and immediately calls Discovery().ServerVersion() against the CRD-specified Kubernetes API endpoint, which is parsed only for URL syntax (url.Parse) with no allow/deny-list for loopback, RFC1918 private ranges, link-local, or cloud-metadata addresses (e.g. 169.254.169.254). A user able to create or update a Cluster CRD can force the controller-manager and apiserver pods to issue outbound requests to arbitrary internal or metadata endpoints.