Microsoft’s confirmation of a new, unpatched Windows Print Spooler bug comes days after researchers noticed that published proof-of-concept code for a different vulnerability was reliably exploiting fully patched Windows machines.

Microsoft’s own misdiagnosis of a Print Spooler flaw that was just patched in June this year also added to the confusion.

In a pre-patch advisory issued late Thursday, Microsoft said a reliable exploit could be launched remotely to take full control of unpatched machines.