Emergency Adobe Update
Adobe released an emergency update for the Adobe Flash browser plugin today for a security issue that is already being exploited.
A critical flaw in Adobe Flash is already being used in a few targeted cases. Particularly at risk are Firefox on Windows XP and Internet Explorer on Windows 7. (Of course, Windows XP is no longer even supported by Microsoft, so if you're using that, you really need to upgrade your whole system anyway.) Adobe Flash on Google Chrome and Internet Explorer on Windows 8 or above should automatically update.
When iPods, iPhones and iPads decided to release browsers that ignored Flash, the formerly popular interface declined in popularity, so if you want to be really safe, you could simply uninstall it from your computer altogether. While some websites still use it for videos and interactive games, if you don't use it for either of those there's not much of a point in having it anyway.