Hello

I have my own VPS running LxAdmin and Lighthttpd but the problem is with a script you can go up a directory into everyone else's websites and files its structured like this:

/home/admin/domain.com/public_html/
/home/admin/otherdomain.com/public_html/

The problem is the "domain.com" can get a php script and go up a few directorys then into "otherdomain.com" files. How would i go around stopping this?