Description of the security update for Microsoft Exchange Server 2019, 2016, and 2013: October 13, 2020

Applies to: Exchange Server 2019Exchange Server 2016Exchange Server 2013

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:

Improvements and fixes


  • Adds prompting for add-ins to be enabled when they originate from an unknown location.

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, confirm 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.

  • When you block third-party cookies in a web browser, you may be continually prompted to trust a particular add-in even though you keep selecting the option to trust it. This issue occurs also in privacy window modes (such as InPrivate mode in Microsoft Edge). This issue occurs because browser restrictions prevent the response from being recorded. To record the response and enable the add-in, you must enable third-party cookies for the domain that's hosting OWA or Office Online Server in the browser settings. To enable this setting, refer to the specific support documentation for the browser.

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: October 13, 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 7 Exchange2019-KB4581424-x64-en.msp 2B93E417D154C1FC044916E1665DAABE93B52F04 4E13914E5D78A335A5F92855F4ABD83B0A6A4859EEC6E8F5BAFC5B4AE6FA9465
Exchange Server 2019 Cumulative Update 6 Exchange2019-KB4581424-x64-en.msp EAF8E42EAA60245280D7AB130D0D67C2CC82BB6D C1E97C7D8616B42D5BABD2B5EA7839E416DB93C5FB28A0BEDA1DA3BC8151E5FD
Exchange Server 2016 Cumulative Update 18 Exchange2016-KB4581424-x64-en.msp A28530243B8031A25661F0AB3886A632251BC0C8 14020874EA999BC77C6ADB5335FB1E995BFCC7B84CD7B1FF76CE0FB87349B0AF
Exchange Server 2016 Cumulative Update 17 Exchange2016-KB4581424-x64-en.msp F32FE4AF499FDAA2E904A3C3C7665712681510F5 835755EAC26B1060F9AA874896D70D0DCC08C0C7A41C50E14C2D8C48A27892B7
Exchange Server 2013 Cumulative Update 23 Exchange2013-KB4581424-x64-en.msp FD3128A4797514EE26BDAF5AC8D3BB720E638B4F CEA9E73CEC3050EC13D8E6A899B3FC61CEA4CA99660C9E192A757AA8C06D689A


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