Microsoft has released security updates for vulnerabilities found in:
Exchange Server 2013
Exchange Server 2016
Exchange Server 2019
These updates are available for the following specific...
Updated May 04, 2021
Version 8.0
Blog Post
Thanks Nino_Bilic I installed patches on 3 node cluster Exchange 2013 last night and so far so good.
jeffc1670 go to https://aka.ms/ExchangeUpdateWizard and it will tell you the steps to update Exchange 2013 CU23
if you have applied March security patch then you may have installed net framework 4.8 so you can skip that.
Don't get download from windows update. Download the patch, use elevated command prompt to run patch .MSP.
Additional step that I did before installing patch is to stop ALL Exchange services manually. during the patch install, I also keep checking the service to make sure the service doesn't restart automatically.
It took me about 1 hour per server.