There are a couple of vulnerabilities in EServ 2.97.
The FTP server doesn't close the sockets that are allocated from using the PASV command. After all ports from 1024 to 5000 are listening (after running a lot of PASV commands in a row) no users can use passive mode anymore until the server is restarted.
This vulnerability is made even worse by the fact that the PASV command is accepted before the user has authenticated.
The FTP server is also vulnerable to the bounce attack. Not only does it not have a restriction on the IP address that the data connection is opened to, but it also does not have a restriction on the target port number either.
The lastest beta version fixes these two vulnerabilities and it can be found at ftp://ftp.eserv.ru/pub/beta/2.98/
. Download the zip file and unzip the exe file inside so it overwrites the exe file from version 2.97.