Description of the security update for Microsoft Exchange Server 2019 and 2016: September 8, 2020

Applies to: Exchange Server 2019Exchange Server 2016

This update rollup is a security update that resolves vulnerabilities in Microsoft Exchange Server. To learn more about these vulnerabilities, see the following security advisory:

Known issues in this update


  • When you try to manually install this security update by double-clicking the update file (.msp) to run it in Normal mode (that is, not as an administrator), some files are not correctly updated.

    When this issue occurs, you don’t receive an error message or any indication that the security update was not correctly installed. However, Outlook Web Access (OWA) and the Exchange Control Panel (ECP) may stop working.

    This issue occurs on servers that are using User Account Control (UAC). The issue occurs because the security update doesn’t correctly stop certain Exchange-related services.

    To avoid this issue, follow these steps to manually install this security update:

    1. Select Start, and type cmd.
    2. In the results, right-click Command Prompt, and then select Run as administrator.
    3. If the User Account Control dialog box appears, verify that the default action is the action that you want, and then select Continue.
    4. Type the full path of the .msp file, and then press Enter.

    This issue does not occur if you install the update through Microsoft Update.

  • Exchange services may remain in a disabled state after you install this security update. This condition does not indicate that the update is not installed correctly. This condition may occur if the service control scripts experience a problem when they try to return Exchange services to their usual state.

    To fix this issue, use Services Manager to restore the startup type to Automatic, and then start the affected Exchange services manually. To avoid this issue, run the security update at an elevated command prompt. For more information about how to open an elevated Command Prompt window, see Start a Command Prompt as an Administrator.

How to get and install the update


Method 1: Microsoft Update

This update is available through Windows Update. When you turn on automatic updating, this update will be downloaded and installed automatically. For more information about how to turn on automatic updating, see Windows Update: FAQ.

Method 2: Microsoft Update Catalog

To get the standalone package for this update, go to the Microsoft Update Catalog website.

Method 3: Microsoft Download Center

You can get the standalone update package through the Microsoft Download Center.

More information


Security update deployment information

For deployment information about this update, see security update deployment information: September 8, 2020

Security update replacement information

This security update replaces the following previously released updates:

File information


File hash information

Update name File name SHA1 hash SHA256 hash
Exchange Server 2019 Cumulative Update 6 Exchange2019-KB4577352-x64-en.msp 5B3B0B62C5E569DD5933C7BA9B1CCC6DB4E345BA 505D471F51C9FCAB7DAB05B5BC1AFD90F29B3C5E220B0BD8C4B2294DC73FB2FA
Exchange Server 2019 Cumulative Update 5 Exchange2019-KB4577352-x64-en.msp BB2831C140538F45CBAC9F819ECBD95A1B07DDAC 5D9DAAF411F0C5DEA72BBD238DACC3852D90EDCAAA4CBA1D909C93ED061EC122
Exchange Server 2016 Cumulative Update 17 Exchange2016-KB4577352-x64-en.msp CE5F53FDE5F3DFE491B80CE27FEA735EBAA929BC 176F74049CC7B9087A7C6190DBD85EC0A1B269FC8EE4F646CF17710B5E97924C
Exchange Server 2016 Cumulative Update 16 Exchange2016-KB4577352-x64-en.msp F6227A7AE5DFDDBE27E8F3C6BB3AD5D3907FCF52 851E0361A4300E44A3F01E20E125191CC1728FE30EA3298B9FA1E3D49AF89000


Exchange server file information

The English (United States) version of this update installs files that have the attributes that are listed in the following tables. The dates and times for these files are listed in Coordinated Universal Time (UTC). The dates and times for these files on your local computer are displayed in your local time together with your current daylight-saving time (DST) bias. Additionally, the dates and times may change when you perform certain operations on the files.

Information about protection and security


Protect yourself online: Windows Security support

Learn how we guard against cyber threats: Microsoft Security