Microsoft s security folks are actually recommending that Firefox users uninstall the buggy add-on. The vulnerability is in an IE component, but there is an attack vector for Firefox users as well. All that is needed is for a user to be lured to a malicious website. Triggering this vulnerability involves the use of a malicious XBAP (XAML Browser Application). The underlying vulnerability is different. Here, the affected process is the Windows Presentation Foundation (WPF) hosting process, PresentationHost.exe.
Source: https://threatpost.com/microsoft-net-plug-exposes-firefox-users-malware-attacks-101609/72334/