CoreGraphics in Apple iOS before 7.1.2 does not properly restrict allocation of stack memory for processing of XBM images, which allows remote attackers to execute arbitrary code or cause a denial of service (application crash) via crafted image data.
http://www.securitytracker.com/id/1030500
http://www.securityfocus.com/bid/68276
http://archives.neohapsis.com/archives/bugtraq/2014-06/0174.html