"Because of the difficulties some users have had entirely removing the add-on, and because of the severity of the risk it represents if not disabled, we contacted Microsoft today to indicate that we were looking to disable the extension and plugin for all users via our blocklisting mechanism," wrote Mozilla Vice President of Engineering Mike Shaver in a "Microsoft agreed with the plan, and we put the blocklist entry live immediately."

Buggy plugins are a growing problem, as cyber criminals have increasingly leveraged flaws in products such as Adobe Flash Player and QuickTime to launch browser-based attacks. Earlier this week, Mozilla launched a site where Firefox users can see if their plugins are up-to-date.