It's not Patch Tuesday, but Windows users should take note of an off-schedule patch that fixes a serious security vulnerability.
The patch fixes a font driver vulnerability that could let a hacker remotely execute code on a compromised Windows machine. Windows Vista, Windows 7, Windows 8.x, Windows RT and RT 8.1, Windows Server 2008, and Windows Server 2012 are all at risk.
Microsoft is pushing the patch through Automatic Update, so if you have updates automatially installed, you don't have to worry (just let your computer do the updates). If you don't have automatic updates turned on, you'll need to manually download and install it.
You can read more about the vulnerabiility, which involves the way Windows Adobe Type Manager Library handles OpenType fonts over at this Microsoft Knowledge Base Article.