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Release Date:

12/8/2020

Version:

1903-OS Build 18362.1256 and 1909-OS Build 18363.1256

NEW 8/5/21
EXPIRATION NOTICE

IMPORTANT As of 8/5/2021, this KB is no longer available from Windows Update, the Microsoft Update Catalog, or other release channels.  We recommend that you update your devices to the latest security quality update. 

NEW 12/8/20
IMPORTANT
Adobe Flash Player will go out of support on December 31, 2020. For more information, see Adobe Flash end of support on December 31, 2020. Flash content will be blocked from running in Flash Player beginning January 12, 2021. For more information, see Adobe Flash Player EOL General Information Page.

UPDATED 12/8/20
REMINDER 
Windows 10, version 1903 has reached end of servicing as of this release dated December 8, 2020. To continue receiving security and quality updates, Microsoft recommends that you update to the latest version of Windows 10. If you want to update to Windows 10, version 1909, you must use the Enablement Package KB4517245(EKB). Using the EKB makes updating faster and easier and requires a single restart. For more information, see Windows 10, version 1909 delivery options.

11/19/20
For information about Windows update terminology, see the article about the types of Windows updates and the monthly quality update types. To view other notes and messages, see the Windows 10, version 1903 update history home page.

Note Follow @WindowsUpdate to find out when new content is published to the release information dashboard.

11/10/20
IMPORTANT
Because of minimal operations during the holidays and the upcoming Western new year, there won’t be a preview release (known as a “C” release) for the month of December 2020. Normal monthly servicing for both B and C releases will resume in January 2021.

Highlights

  • Updates to improve security when using Microsoft Edge Legacy.

  • Updates to improve security when using Microsoft Office products.

Improvements and fixes

This security update includes quality improvements. Key changes include:

  • This build includes all the improvements from Windows 10, version 1903.

  • No additional issues were documented for this release.

Note This release also contains updates for Microsoft HoloLens (OS Build 18362.1088) released December 8, 2020. Microsoft will release an update directly to the Windows Update Client to improve Windows Update reliability on Microsoft HoloLens that have not updated to this most recent OS Build.

This security update includes quality improvements. Key changes include:

  • Addresses an issue that might cause system and user certificates to be lost when updating a device from Windows 10, versions 1809 or later to a later version of Windows 10.

  • Security updates to Microsoft Edge Legacy, the Microsoft Graphics Component, Windows Media, Windows Fundamentals, and Windows Virtualization. 

If you installed earlier updates, only the new fixes contained in this package will be downloaded and installed on your device.

For more information about the resolved security vulnerabilities, please refer to the new Security Update Guide website.

Windows Update Improvements

Microsoft has released an update directly to the Windows Update client to improve reliability. Any device running Windows 10 configured to receive updates automatically from Windows Update, including Enterprise and Pro editions, will be offered the latest Windows 10 feature update based on device compatibility and Windows Update for Business deferral policy. This doesn't apply to long-term servicing editions.

Known issues in this update

Microsoft is not currently aware of any issues with this update.

How to get this update

Before installing this update

Microsoft strongly recommends you install the latest servicing stack update (SSU) for your operating system before installing the latest cumulative update (LCU). SSUs improve the reliability of the update process to mitigate potential issues while installing the LCU and applying Microsoft security fixes. For general information about SSUs, see Servicing stack updates and Servicing Stack Updates (SSU): Frequently Asked Questions.

If you are using Windows Update, the latest SSU (KB4586863) will be offered to you automatically. To get the standalone package for the latest SSU, search for it in the Microsoft Update Catalog.

Install this update

Release Channel

Available

Next Step

Windows Update and Microsoft Update

Yes

None. This update will be downloaded and installed automatically from Windows Update.

Microsoft Update Catalog

Yes

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

Windows Server Update Services (WSUS)

Yes

This update will automatically sync with WSUS if you configure Products and Classifications as follows:

Product: Windows 10, version 1903 and later

Classification: Security Updates

File information

For a list of the files that are provided in this update, download the file information for cumulative update 4592449

Note Some files erroneously have “Not applicable” in the “File version” column of the CSV file. This might lead to false positives or false negatives when using some third-party scan detection tools to validate the build.

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