Kyverno's PolicyException objects can be created in any namespace by default

Kyverno is a policy engine designed for Kubernetes. A kyverno ClusterPolicy, ie. "disallow-privileged-containers," can be overridden by the creation of a PolicyException in a random namespace. By design, PolicyExceptions are consumed from any namespace. Administrators may not recognize that this allows users with privileges to non-kyverno namespaces to create exceptions. This vulnerability is fixed in 1.13.0.