Adobe Flash has been riddled with security holes for years, and is perhaps the most commonly exploited piece of software on the planet. Adobe recently announced it would be no longer updating or distributing Flash after 2020. Firefox 55 users will be forced to specifically give permission for the forlorn Flash plugin to run, giving surfers the ability to choose which websites they want to grant permission to play Flash content. Chrome, Safari and Microsoft Edge have been switching users over to HTML5 by default since late last year.”]
Source: https://www.bitdefender.com/blog/hotforsecurity/at-last-firefox-puts-another-nail-in-flashs-coffin/