It's based on HardenedJS.org The sandbox itself is tight, there's a bug bounty even. The same technology is behind metamask snaps - plugins in a browser exten

It's based on HardenedJS.org The sandbox itself is tight, there's a bug bounty even. The same technology is behind metamask snaps - plugins in a browser extension. And Moddable has their own implementation The biggest problem is endowing too powerful capabilities. We've got ambitious plans for isolating DOM, but that already failed once before.