If any GNU/Linux distro has four unpatched zero day exploits at the same time, I'll eat my hat.
Yeah - as i said - breaking into a fully patched desktop Linux with software only from signed repos using a 0-day is itself highly unlikely.
+ Add Noscript/Flashblock = Very highly unlikely (A critical 0-day vulnerabilities which do not require javascripts/canvas/html5/iframes/advanced stuff are VERY rare)
+ Add Virtual Machine = Practically impossible