The gdImageCropThreshold function in gd_crop.c in the GD Graphics Library (aka libgd) before 2.2.3, as used in PHP before 7.0.9, allows remote attackers to cause a denial of service (application crash) via an invalid color index.
https://security.gentoo.org/glsa/201612-09
https://libgd.github.io/release-2.2.3.html
https://github.com/libgd/libgd/commit/6ff72ae40c7c20ece939afb362d98cc37f4a1c96
https://github.com/libgd/libgd/commit/1ccfe21e14c4d18336f9da8515cd17db88c3de61
http://www.ubuntu.com/usn/USN-3030-1
http://www.securitytracker.com/id/1036276
http://www.securityfocus.com/bid/91509
http://www.openwall.com/lists/oss-security/2016/06/30/1
http://www.debian.org/security/2016/dsa-3619
http://rhn.redhat.com/errata/RHSA-2016-2750.html
http://lists.opensuse.org/opensuse-updates/2016-09/msg00078.html
http://lists.opensuse.org/opensuse-updates/2016-08/msg00086.html