Chrome has controls to not allow an extension free reign on all sites despite it asking for them. Allow only on specified sites. it's not a default for some reason, but if the extension doesn't have access then it can't do anything, bad or good.

Of course it doesn't help that it's a finance site that disables paste for which I need an extension to reenable, but at least I'm not letting the rest of my extensions get at my banking web session.