Mozilla release and emergency update for Firefox 40 on August 13, 2015 with Firefox 40.0.2 release.This update addressed these issues:

• Fix a startup crash with some combination of hardware and drivers (1160295)
• mozalloc.lib was missing from the xulrunner package (1168291)
• Enabled API allowing Windows 10 users to open settings dialog (1193196)

Firefox ESR was unaffected by the above issues and was not updated. User can get the update by going to Firefox: Help > About Firefox and following the prompts or can manually download and install via the getfirefox.com site. The next planned release is Firefox 41 on September 22, 2015.