Microsoft has released a critical patch via Windows Update today that fixes a vulnerability that affects EVERY. SINGLE. MODERN. version of Windows, including Windows Server 2003/2008/2012, Vista, 7, 8, 8.1, and Windows RT.
The patch, named MS14-066, closes up a hole that nay allow an attacker to remotely trigger code on your machine using specially crafted snippets. Microsoft says they don't have any reports that someone may have actually used this, but it's still a good idea to get the patch.. This just like any other security patch, but the HUGE number of machines affected means it's good to make sure your system is up to date. You can grab the patch from Windows Update right now.