Cumulative Update 20 shows in Programs and Features if installing Exchange Server 2013 Cumulative Update 22
Original KB number: 4492759
After you successfully install Cumulative Update 22 for Exchange Server 2013, the Programs and Features item in Control Panel lists the installation as Exchange Server 2013 Cumulative Update 20.
This issue occurs because Exchange Server Setup does not update the version string in the registry correctly.
Follow the steps in this section carefully. Serious problems might occur if you modify the registry incorrectly. Before you modify it, back up the registry for restoration in case problems occur.
To fix this issue, change the registry key for the update display name. To do this, follow these steps:
On the Start menu, select Run, type regedit in the Open box, and then select OK.
Locate the following subkey:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Microsoft Exchange v15
In the details pane, locate and double-click the DisplayName item.
In the Value data box, change the string to the following value:
Microsoft Exchange Server 2013 Cumulative Update 22
Select OK to save the change.