Ubuntu Security Notice USN-164-1 – Max Vozeler discovered that the the pstopnm conversion tool did not use the -dSAFER option when calling ghostscript. This option prohibits file operations and calling commands within PostScript code. This flaw could be exploited by an attacker to execute arbitrary code if he tricked an user (or an automatic server) into processing a specially crafted PostScript document with pstopnm.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/39231/USN-164-1.txt
Source: https://packetstormsecurity.com/files/39231/Ubuntu-Security-Notice-164-1.html