Today we are announcing June 2018 as the final end of life date for Firefox support on Windows XP and Vista. As one of the few browsers that continues to support Windows XP and Vista, Firefox users on these platforms can expect security updates until that date. Users do not need to take additional action to receive those updates.
We strongly encourage our users to upgrade to a version of Windows that is supported by Microsoft. Unsupported operating systems receive no security updates, have known exploits, and are dangerous for you to use.
For more information please visit the Firefox support page.