Buffer overflow in mtr 0.46 and earlier, when installed setuid root, allows local users to access a raw socket via a long MTR_OPTIONS environment variable.
http://www.iss.net/security_center/static/8367.php
http://www.debian.org/security/2002/dsa-124
http://archives.neohapsis.com/archives/bugtraq/2002-03/0048.html