wzdftpd 0.5.4 allows remote authenticated users to execute arbitrary commands via shell metacharacters in the SITE command.
http://www.securityfocus.com/bid/14935
http://www.debian.org/security/2006/dsa-1006
http://secunia.com/advisories/16936
http://archives.neohapsis.com/archives/fulldisclosure/2005-09/0646.html