Earlier this week, Microsoft quietly released a new patch, KB5021751. Some users reported that Windows 10/11 system received related push.
Microsoft has not shied away from the use of patches, stating that the purpose is to find out-of-date versions of Office, including Office 2013/2010 and 2007, but the purpose is unclear.
There is speculation that Microsoft may be trying to determine the number of Office installations currently in place for 2013/2010/2007. The patch will only run silently once and will not install anything else on the user's computer.
With Office 2013 set to end in April 2023, Microsoft is pushing Microsoft 365 (formerly Office 365).
Of course, there are concerns about the high volume of pirated Office 2013 installs. Is Microsoft trying to get tough?