Heap-based buffer overflow in the read_xwd_cols function in file-xwd.c in the X Window Dump (XWD) plug-in in GIMP 2.6.9 and earlier allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via an X Window System (XWD) image dump with more colors than color map entries.
https://security.gentoo.org/glsa/201603-01
https://bugzilla.redhat.com/show_bug.cgi?id=953902
http://www.ubuntu.com/usn/USN-2051-1