The xpc_data_get_bytes function in libxpc in Apple OS X before 10.10.2 does not verify that a dictionary's Attributes key has the xpc_data data type, which allows attackers to execute arbitrary code by providing a crafted dictionary to sysmond, related to an "XPC type confusion" issue.
http://lists.apple.com/archives/security-announce/2015/Jan/msg00003.html
http://support.apple.com/HT204244
http://www.exploit-db.com/exploits/35742/
http://www.securityfocus.com/bid/71992
http://www.securitytracker.com/id/1031650
https://code.google.com/p/google-security-research/issues/detail?id=121