Directory traversal vulnerabilities in multiple FTP clients on UNIX systems allow remote malicious FTP servers to create or overwrite files as the client user via filenames containing /absolute/path or .. (dot dot) sequences.
http://www.securityfocus.com/bid/6360
http://www.kb.cert.org/vuls/id/210409
http://www.iss.net/security_center/static/10821.php
http://marc.info/?l=bugtraq&m=103962838628940&w=2
http://archives.neohapsis.com/archives/vulnwatch/2002-q4/0102.html