Virtuozzo managed VPS, cPanel, RedHat 7.3

ALL client's accounts are jailshells. But, in sFTP over SSH2 with jailshell enabled they can see some folders outside their home dir:

bin
dev
home
etc
lib
proc
tmp
usr
var.

And they can see the files inside them. They can't delete them, but can download them.

Is there any way to prevent this, I am not comfortable with this at all?