source: http://www.securityfocus.com/bid/78/info

makebootdisk creates the file /tmp/return insecurely and follows symbolic links. An attacker can create a symbolic link from /tmp/return to any file and wait for root to run the program. This will clober the target file. The file created has permissions -rw-r--r--.

$ ln -s /tmp/return /etc/passwd
< wait for root to run makebootdisk >