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.
A malicious builder peer may be able to request an in-context file by name from the host and receive the contents of whatever the name resolves to, even when it resolves outside the build context. This vulnerability is addressed in container version 1.2.0.
Users who connect to malicious registries with hostnames matching the bypass patterns will have their registry credentials exposed in plaintext. This issue is fixed in container version 0.12.3.