Linux - Slackware 3.0 and RedHat 2.1 verified, others unknown.
Local users can get superuser privleges.
Some Linux distributions come with dip setuid root by default. There are multiple points in dip where an unbounded buffer is used with user supplied data making possible a stack overflow. It is suggested that at least until the source has been further scrutinized that dip not be setuid unless necessary. If you must have dip setuid, place it in a group where it can only be executed by trusted users.