Summary
If an attacker can write to the filesystem of a container k8s cluster container, they can plant an exec credential plugin in /etc/kubernetes/admin.conf. kubectl will run that plugin as the macOS host user the next time someone pulls the cluster's kubeconfig onto the host with container k8s write-config or create and then runs kubectl against it — turning filesystem access inside an untrusted Linux container into arbitrary command execution on the host. This vulnerability is addressed in Container version 1.5.0.