An attacker may be able to access directories outside the FTP root
The remote host is running wu-ftpd 2.6.2 or older. There is a bug in this version which may allow an attacker to bypass the restricted-gid feature and gain unauthorized access to otherwise restricted directories. In addition, this version is prone to a remote overflow in the S/KEY authentication.
Upgrade to wu-ftpd 2.6.3 or later.