acFTP 1.4 does not properly handle when an invalid password is provided by the user during authentication, which allows remote attackers to hide or misrepresent certain activity from log files and possibly gain privileges.
http://www.securityfocus.com/archive/1/300929
http://www.iss.net/security_center/static/10681.php
http://securityreason.com/securityalert/3334
http://archives.neohapsis.com/archives/vulnwatch/2002-q4/0088.html