LPRng Incorrect Installation Permissions Vulnerability
A vulnerability exists in the default installation of LPRng, versions 3.6.1 through 3.6.15. The 'lpd' program is inadvertently installed setuid root in these installations, while it should only be owned by root, and not setuid. According to the author of LPRng, it is possible for arbitrary users to append logging information using the -L option, assuming the following conditions are true:
The lpd server is not running
lpd is installed setuid root
Non-root users can execute lpd
The file to be altered exists
The file is writable by the user/group lpd runs as (daemon/daemon).
Files that can be appended to include files in the spool queues.