Heap-based buffer overflow in the IsPixelGray function in MagickCore/pixel-accessor.h in ImageMagick 7.0.3.8 allows remote attackers to cause a denial of service (out-of-bounds heap read) via a crafted image file. NOTE: this vulnerability exists because of an incomplete fix for CVE-2016-9556.
http://www.openwall.com/lists/oss-security/2016/12/02/12