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://lists.apple.com/archives/security-announce/2013/Oct/msg00004.html
http://lists.apple.com/archives/security-announce/2013/Sep/msg00006.html
http://secunia.com/advisories/54886