The posix_spawn system call in the XNU kernel in Apple Mac OS X 10.8.x does not properly validate the data for file actions and port actions, which allows local users to (1) cause a denial of service (panic) via a size value that is inconsistent with a header count field, or (2) obtain sensitive information from kernel heap memory via a certain size value in conjunction with a crafted buffer.
http://www.syscan.org/index.php/sg/program/day/2
http://www.securitytracker.com/id/1029054
http://support.apple.com/kb/HT5934
http://secunia.com/advisories/54886
http://lists.apple.com/archives/security-announce/2013/Sep/msg00006.html
http://lists.apple.com/archives/security-announce/2013/Oct/msg00004.html