Gave access to one directory (site) FTP, will they be able to access other directories with the help of hacking?

Question

FTP

Hello!
I gave a freelancer access to FTP, only for one site (var/nickname/data/www/site.ru). Created an FTP account with a new username and password on the server and gave it to the freelancer.
Is there a way to hack through one directory? I'm just afraid of the person hacking and entering the main sites.
I gave him access to the test site so that he could make a module for the site.

Answer 1

If the security policy on the server is configured incorrectly and other sites have folders with 777 permissions, then yes, hacking is possible.

Answer 2

maybe if you upload some kind of exploit that can go higher on the level.