Microsoft usually releases patches once a month – but occasionally the vulnerability is bad enough that they release the patch immediately. This is one of those patches – download and install it today!

Microsoft Posts Patch for Critical Vulnerability, Download It Now
Microsoft has released a critical patch via Windows Update today that seals up a vulnerability that affects every modern version of Windows, including Windows Server 2003/2008/2012, Vista, 7, 8, 8.1, and Windows RT.