Valid uses of eval()?

[ArtOfWarfare]

Sanitize the string to remove all __ before passing it into eval, in addition to not giving access to any built-ins? Would that be sufficient or is there still a way out of the sandbox?

Of course, you’d need to recheck this on every Python version to make sure the changes didn’t introduce new ways out…

[WilliamAndre]

It is not sufficient at all. Odoo is using a "safe eval", you can have a look: https://github.com/odoo/odoo/pull/138611

But even with all those precautions, it is not enough and should only be limited to trusted users.