The output function in gd_gif_out.c in the GD Graphics Library (aka libgd) allows remote attackers to cause a denial of service (out-of-bounds read) via a crafted image.
https://github.com/libgd/libgd/issues/209
http://www.ubuntu.com/usn/USN-3030-1
http://www.openwall.com/lists/oss-security/2016/07/05/7
http://www.openwall.com/lists/oss-security/2016/07/05/6
http://www.debian.org/security/2016/dsa-3619
http://lists.opensuse.org/opensuse-updates/2016-09/msg00078.html
http://lists.opensuse.org/opensuse-updates/2016-08/msg00086.html