Microsoft has released security updates (SUs) for vulnerabilities found in:
Exchange Server 2013
Exchange Server 2016
Exchange Server 2019
IMPORTANT: Starting with this release of Securit...
Updated May 27, 2022
Version 21.0
Blog Post
Why does SetupAssist script show the current build as CU22 when the Exchange 2016 server has CU23 installed? Could this be why I cannot get the May 2022 SU installed?
Found that these results are consistent across servers that have been successfully updated. A bit confusing.
With that said, after working with support, it appears CU23 (which we installed 3 weeks ago "successfully") failed to update all of the registry keys under 'HKEY_CLASSES_ROOT\Installer\Products' properly and was causing the May 2022 SU install to fail. We compared reg key values from a server that updated successfully to the server that was failing to update, replaced the reg keys and was able to get the SU installed successfully.
Lastly, not sure I'm comfortable with the state of the server after the "successful" CU23 update and may build a new set of servers to migrate to.