Unfortunately, some sites are abusing the Firefox logo to trick users into installing malware. Since Firefox has a built-in updater, you should never accept files pushed by websites claimed to be Firefox updates.

See also:

• I found a fake Firefox update
• Update Firefox to the latest release (using the "About Firefox" dialog)

The ongoing "attack" against Firefox users seems to be delivered through ad networks used by popular sites. If you do not already use an extension to block unwanted ads, you might consider trying one out. For example:

https://addons.mozilla.org/firefox/addon/ublock-origin/

cissyw said

I am getting emergency update notes for security. But the address does not look right.

If this is from a url that is not a *.mozilla.org url then it likely is not legit.