Kevin Backhouse discovered that apport would read a user-supplied configuration file with elevated privileges. By replacing the file with a symbolic link, a user could get apport to read any file on the system as root, with unknown consequences.
https://usn.ubuntu.com/usn/usn-4171-2
https://usn.ubuntu.com/usn/usn-4171-1
http://packetstormsecurity.com/files/172858/Ubuntu-Apport-Whoopsie-DoS-Integer-Overflow.html