The kernel in Apple Mac OS X 10.4 through 10.4.10 does not reset the current Mach Thread Port or Thread Exception Port when executing a setuid program, which allows local users to execute arbitrary code by creating the port before launching the setuid program, then writing to the address space of the setuid process.
https://exchange.xforce.ibmcloud.com/vulnerabilities/38466
http://lists.apple.com/archives/security-announce/2007/Nov/msg00002.html