March 2021 Exchange Server Security Updates for older Cumulative Updates of Exchange Server

@Nino Bilic  Hello Nino. Thanks for your response.   https://docs.microsoft.com/en-us/exchange/troubleshoot/client-connectivity/exchange-security-update-issues#option-2 does appear to give you a sort of a way to check that https://support.microsoft.com/en-us/topic/description-of-the-security-update-for-microsoft-exchange-server-2019-2016-and-2013-march-2-2021-kb5000871-9800a6bb-0a21-4ee7-b9da-fa85b3e1d23b is installed however I will make two comments:

1) That article is a very good generic troubleshooting article that has received some updates related to https://support.microsoft.com/en-us/topic/description-of-the-security-update-for-microsoft-exchange-server-2019-2016-and-2013-march-2-2021-kb5000871-9800a6bb-0a21-4ee7-b9da-fa85b3e1d23b but does not acknowledge this. The version number returned by Get-Command Exsetup.exe | ForEach {$_.FileVersionInfo} is 15.02.0792.010 which would be the version # for CU8 with the hotfix and not for the original CU8 - that value is 15.02.0792.003 . So this article is misleading in that respect and confusing to the installer.  The article is also confusing in that has some https://support.microsoft.com/en-us/topic/description-of-the-security-update-for-microsoft-exchange-server-2019-2016-and-2013-march-2-2021-kb5000871-9800a6bb-0a21-4ee7-b9da-fa85b3e1d23b specific values but does not acknowledge this

2) If you use WAC or get-hotfix against a Windows 2019 Core server you will see the updates that have been installed on that server. However this is not the case for the https://support.microsoft.com/en-us/topic/description-of-the-security-update-for-microsoft-exchange-server-2019-2016-and-2013-march-2-2021-kb5000871-9800a6bb-0a21-4ee7-b9da-fa85b3e1d23b update on the systems I have installed it on, so I believe that this is a problem with this update.  I don't think installing an update on a Windows server and not being able to verify that it is installed using typical methods is a very desirable situation.  Why wouldn't it show up in WAC or via a simple get-hotfix command?  A script using get-hotfix or WAC or even a 3rd party tool not being able to find the installation of https://support.microsoft.com/en-us/topic/description-of-the-security-update-for-microsoft-exchange-server-2019-2016-and-2013-march-2-2021-kb5000871-9800a6bb-0a21-4ee7-b9da-fa85b3e1d23b is a problem.