tnftpd before 20080929 splits large command strings into multiple commands, which allows remote attackers to conduct cross-site request forgery (CSRF) attacks via unknown vectors, probably involving a crafted ftp:// link to a tnftpd server.
Multiple signal handler race conditions in lukemftpd (aka tnftpd before 20040810) allow remote authenticated attackers to cause a denial of service or execute arbitrary code.