I have just reactivated the guest session in Ubuntu, because several people use my laptop on a temporary basis. I wanted to know if there are any security issues with using a guest session, and if this means someone could access my computer.
SnapOverflow
They shouldn't be able to access any of your files, your history or anything contained within your home directory (settings etc..). I'm sure if they were persistent enough they could get through, but I wouldn't worry about it.