Microsoft has released and out-of-band update (that means, before the 2nd Tuesday of next month).
This is an important update.
True is that with automatically update selected then you will be updated, but not until you next update cycle.
Control Panel | Windows Update | Check for Updates (left side)
Do this whether or not Windows Update tells you that you are up-to-date.
Here is a well-written article on this matter. Microsoft releases out-of-band security update to plug .NET hole | ZDNet
If this has already been mentioned elsewhre, I apologize.