vserver in util-vserver 0.30.209 executes a command as root when the suexec userid parameter is invalid and non-numeric, which might cause local users to inadvertently execute dangerous commands as root.
https://savannah.nongnu.org/patch/?func=detailitem&item_id=4966
https://savannah.nongnu.org/bugs/?func=detailitem&item_id=15996