Hardly fear mongering, is the flay possible/feasible, etc. it doesn't matter if they are unaware of any attacks. Being unaware is hardly a glowing testimony that it isn't a problem. If/and when it does come to their knowledge it will be a bit late in the day.
You can hardly call it fear mongering when it is Microsoft doing the fear mongering as you call it.
Microsoft have warned about a flaw on the Internet Explorer browser, that could allow hackers to take control of unprotected computers.