Sub server FTP User security

Hi,

I am curious to know can ftp user for one site can read other site config files??

For example :- i have parent server with domain1.com and wordpress is installed, now i am creating subserver domain2.com and assigning one FTP user for that directory only. And creating another subserver domain3.com And another one FTP user for that directory only. Now my question is :-

1.) Can domain2.com FTP user read parent server wordpress config files by executing php script? 2.) Can domain2.com FTP user read domain3.com files?

If yes is there any way to prevent that?