Microsoft claims that the KB5021751 update protects users’ privacy while scanning for and identifying the number of customers running outdated or near-end-of-life Office versions.
Microsoft explained in its accompanying support document that this update was intended to assist the company in identifying the number of Windows users who were running outdated or soon-to-be-outdated Office software that would no longer be supported or had reached the end of support. These include Office 2013, which will be phased out later this year, Office 2010, which has already been phased out, and Office 2007, which was phased out in 2012.
“This update is intended to help Microsoft identify the number of users who are running out-of-support (or soon to be out-of-support) versions of Office, including Office 2013, Office 2010, and Office 2007. Versions of Office that are no longer supported do not receive security updates that provide the latest protections against known vulnerabilities. Also, unsupported versions might face performance and reliability issues over time,” Microsoft said.
However, the advisory does not specify what Microsoft intends to do with this data once it has been transmitted to its servers. If you do not want to install this update, you can opt out of receiving updates for other Microsoft products by going to Windows Update > Advanced Options.
The sources for this piece include an article in BleepingComputer.