The ReadGIFImage function in coders/gif.c in ImageMagick before 6.7.8-8 allows remote attackers to cause a denial of service (memory corruption and application crash) via a crafted comment in a GIF image.
https://bugs.launchpad.net/ubuntu/+source/imagemagick/+bug/1218248
http://www.ubuntu.com/usn/USN-1949-1
http://www.imagemagick.org/script/changelog.php
http://www.debian.org/security/2013/dsa-2750
http://secunia.com/advisories/54671