Microsoft published a Security Advisory this week and asked all of its partners to help their clients update their machines as soon as possible.
The advisory, published here, details an issue with the Active Template Library used by developers. If the vulnerability is maliciously leveraged, users of Internet Explorer could be affected by having their system security breached.
If your PC is not managed by your service provider, just run Windows Update and install the updates offered for your PC. If that’s not appropriate for some reason, apply the patch individually using the download from Microsoft.