Directory traversal vulnerability in FTP Serv-U before 2.5i allows remote attackers to escape the FTP root and read arbitrary files by appending a string such as "/..%20." to a CD command, a variant of a .. (dot dot) attack.
https://exchange.xforce.ibmcloud.com/vulnerabilities/5639
http://marc.info/?l=bugtraq&m=97604119024280&w=2
http://archives.neohapsis.com/archives/bugtraq/2000-12/0043.html