This isn't my thing, so with my ignorance on anything 'VM' stated..
I was under the impression that running a virtual OS was failproof safe, it being in fact one of its key advantages; has that changed, or was it never the case?
I get what i'm reading here, i just thought that it being Virtual and isolated, such an occurence was (supposed to be?) impossible.
That is actually one of the corner stones of the latest bugs in intel. Those bugs are nasty to virtual systems and in a way they allows an attack on a host through the guest system.