A flaw was found in the community.proxmox Ansible collection's
proxmox_pct_remote connection plugin. The _build_pct_command()
method constructs a pct exec command string using unquoted string
concatenation and passes it to the Proxmox host's shell via
Paramiko. Shell metacharacters in the command (such as >, |, ;, &&,
or $()) are interpreted on the host instead of inside the target
LXC container, allowing commands intended for an unprivileged
container to execute on the hypervisor host as root. This
constitutes a container-to-host trust boundary crossing. The
put_file and fetch_file methods in the same plugin correctly use
shell quoting, indicating this is an oversight on the exec path.