KLA11492
Bypass security restrictions vulnerability in Microsoft Exchange Server

Microsoft has released an update for Microsoft Exchange Server that provides enhanced security as a defense in depth measure, preventing crashes from uploading certain file types.

Microsoft Exchange Server 2019
Microsoft Exchange Server 2019 Cumulative Update 1
Microsoft Exchange Server 2013 Cumulative Update 22
Microsoft Exchange Server 2016 Cumulative Update 11
Microsoft Exchange Server 2016 Cumulative Update 12
Microsoft Exchange Server 2010 Service Pack 3

Install necessary updates from the KB section, that are listed in your Windows Update (Windows Update usually can be accessed from the Control Panel)