URGENT: This is an emergency bulletin to let you know you that there is a zero day vulnerability in the doing the rounds that affects Firefox web browsers and the Tor browser bundle. The vulnerability only emerged a few hours ago.
We recommend that you switch to a non-Firefox based browser like Chrome until the Firefox dev team has had a chance to release a fix. That should happen quickly due to the severity of of the issue.
We would like to encourage you to share this alert with everyone you know especially if they use Firefox or the Tor browser. The impact of this may be wide-spread, and we also suspect that WordPress websites may be used as a watering hole to infect vulnerable web browsers using this new exploit.
More information can be found here