February 9, 2021-KB4601887 Cumulative Update for .NET Framework 3.5, 4.7.2 and 4.8 for Windows 10, version 1809 and Windows Server, version 2019
Release Date:
February 9, 2021Version:
.NET Framework 3.5, 4.7.2 and 4.8Summary
Security Improvements
This security update addresses a denial of service vulnerability in .NET Framework. For more information please see CVE-2021-24111.
Quality Improvements
For a list of improvements that were released with this update, please see the article links in the Additional Information section of this article.
Known issues in this update
Symptom |
After installing this update, WPF apps may crash with a callstack similar to
This occurs when disposing an HwndSource whose RootVisual is null, a situation that arises in Visual Studio when docking or splitting windows, and could arise in other apps. |
Workaround |
This issue was resolved in KB4601558 for .NET Framework 4.7.2, and KB4601555 for .NET Framework 4.8. |
Additional information about this update
The following articles contain additional information about this update as it relates to individual product versions.
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4601060 Description of the Cumulative Update for .NET Framework 3.5 and 4.7.2 for Windows 10, version 1809 and Windows Server, version 2019 (KB4601060)
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4601055 Description of the Cumulative Update for .NET Framework 3.5 and 4.8 for Windows 10, version 1809 and Windows Server, version 2019 (KB4601055)
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: Classification: Security Updates |
Information about protection and security
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Protect yourself online: Windows Security support
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Learn how we guard against cyber threats: Microsoft Security