Another buggy patch fixed over the past few days was the Office update, first released back in August. This was apparently misconfigured so that customers who use Microsoft update tools such as Windows Server Update Services (WSUS) were given bad scan results. Customers who use Microsoft's tools may believe they're fully patched, when in fact they're not due to this bug, said Eric Schultze, an independent security consultant.

Those customers should re-run their update tools to be sure that they're patched, he added.

Microsoft said it also corrected some "detection entries" and "file and registry key verification information" in an update to the patch, released Wednesday.

The company declined to provide any further explanation of the issues, referring inquiries to its online documentation.