IDE SCM in Apple Xcode before 7.2 does not recognize .gitignore files, which allows remote attackers to obtain sensitive information in opportunistic circumstances by leveraging the presence of a file matching an ignore pattern.
https://support.apple.com/HT205642
http://www.securitytracker.com/id/1034340
http://lists.apple.com/archives/security-announce/2015/Dec/msg00004.html