In containerized-data-importer (CDI), the aggregated cdi.kubevirt.io:view ClusterRole, intended to provide read-only access to CDI resources, includes a rule granting create on the datavolumes/source subresource. CDI's DataVolume clone authorization accepts this permission as sufficient to authorize cloning the contents of any PVC the caller can name, without requiring write access to the source namespace. A user or service account bound to the view role, commonly granted cluster-wide via ClusterRoleBinding, who also has ordinary write access (edit/admin) to any single namespace, can use this to exfiltrate the contents of any PVC in the cluster into a namespace they control, bypassing namespace isolation and the read-only guarantee of the view role.
Until a fix is available, cluster administrators should avoid granting cdi.kubevirt.io:view (or the built-in Kubernetes view role, which aggregates it) via cluster-wide ClusterRoleBinding. Prefer namespace-scoped RoleBindings, and audit which namespaces grant both view-equivalent access and separate edit/admin access to the same identities, since that combination is what enables cross-namespace data exfiltration.