Office Viewer in Apple iOS before 8.4.1 and OS X before 10.10.5 allows remote attackers to read arbitrary files via an XML document containing an external entity declaration in conjunction with an entity reference, related to an XML External Entity (XXE) issue.
https://support.apple.com/kb/HT205031
https://support.apple.com/kb/HT205030
https://support.apple.com/HT205373
http://www.securitytracker.com/id/1033275
http://www.securityfocus.com/bid/76343
http://lists.apple.com/archives/security-announce/2015/Oct/msg00000.html
http://lists.apple.com/archives/security-announce/2015/Aug/msg00002.html
http://lists.apple.com/archives/security-announce/2015/Aug/msg00001.html