hi, this is a scam tactic that is trying to trick you into installing malware, so don't download or execute this kind of stuff just because of a popup or redirect on a website! updates are handled automatically by firefox so you don't have to download anything for that (and you can always initiate a manual check for updates in the firefox menu ≡ > help ? > about firefox).

we suspect this is coming form "malvertising" (=ads placed on legitimate websites that redirect you to this fraudulent message), so using an adblocking addon like https://addons.mozilla.org/firefox/addon/ublock-origin/ would also help with that.

I found a fake Firefox update

Thanks for your reply. I didn't click on it as I have never seen an update come through like that and fortunately noticed the URL's were not Mozilla's. I find it disturbing that Yahoo does not control malware on their site. I merely had the browser open and had not clicked on any of the articles. The browser window opened on its own.

unfortunately we had reports from users who said it was happening on other major sites as well. these advertising networks are totally out of control :-/