Microsoft has released a security update for Adobe Flash Player that Adobe considers critical. The vulnerability allows an attacker to crash a system or take control of it. If you have automatic installation of updates turned on, you don't need to take any action because the app is distributed via Windows Update. Otherwise, install the update as soon as possible.
Internet Explorer 10 for Windows 8 and Internet Explorer 11 for Windows 8.1 are affected, as are other browsers on other operating systems.
For more information, see Security Bulletin APSB14-13 and CVE-2014-0515.