Apple Type Services (ATS) in Apple OS X before 10.11.5 allows attackers to bypass intended FontValidator sandbox-policy restrictions and execute arbitrary code in a privileged context via a crafted app.
https://support.apple.com/HT206567
http://www.zerodayinitiative.com/advisories/ZDI-16-360
http://www.securitytracker.com/id/1035895
http://www.securityfocus.com/bid/90696
http://lists.apple.com/archives/security-announce/2016/May/msg00004.html