TruBlueEnvironment for MacOS 10.2.3 and earlier allows local users to overwrite or create arbitrary files and gain root privileges by setting a certain environment variable that is used to write debugging information.
http://www.securityfocus.com/bid/6859
http://www.iss.net/security_center/static/11332.php
http://www.atstake.com/research/advisories/2003/a021403-1.txt
http://lists.apple.com/archives/security-announce/2003/Feb/25/applesa20030225macosx102.txt