The gnapster and knapster clients for Napster do not properly restrict access only to MP3 files, which allows remote attackers to read arbitrary files from the client by specifying the full pathname for the file.
http://www.securityfocus.com/bid/1186
http://archives.neohapsis.com/archives/bugtraq/2000-05/0127.html
http://archives.neohapsis.com/archives/bugtraq/2000-05/0124.html