Podman: Malformed Image can trick podman run into leaking host environment variables into the container

Podman is a tool for managing OCI containers and pods. From 1.8.1 until 5.8.4, a container image that contains a environment variable with just a key and no value can trick podman into passing that variable from the host into the container. This is made worse by the fact that using an asterisk (*) will cause podman to pass all host variables into the container. So essentially a malicious image can exfiltrate all podman environment variables that are set in the session from where the container is launched. This vulnerability is fixed in 5.8.4 and 6.0.0.