The Text Formats component in Apple OS X before 10.10.5, as used in TextEdit, allows remote attackers to read arbitrary files via a text file containing an XML external entity declaration in conjunction with an entity reference, related to an XML External Entity (XXE) issue.
https://support.apple.com/kb/HT205031
http://www.securitytracker.com/id/1033276
http://www.securityfocus.com/bid/76340
http://lists.apple.com/archives/security-announce/2015/Aug/msg00001.html