April 9, 2024-KB5036620 Cumulative Update for .NET Framework 3.5 and 4.8.1 for Windows 11, version 22H2 and Windows 11, version 23H2
Applies To
.NETRevised July 7, 2025: Updated 'How to get this update' section.Â
Release Date:April 9, 2024
Version: .NET Framework 3.5 and 4.8.1
The April 9, 2024 update for Windows 11, version 22H2 and Windows 11, version 23H2 includes security and cumulative reliability improvements in .NET Framework 3.5 and 4.8.1. We recommend that you apply this update as part of your regular maintenance routines. Before you install this update, see the Prerequisites and Restart requirement sections.
Summary
Security Improvements
CVE-2024-21409 - .NET Framework Remote Code Execution Vulnerability This security update addresses a remote code execution vulnerability detailed in CVE-2024-21409.
.NET Framework Defense in Depth Vulnerability This security update addresses an issue where version of the OSS zlib library is out of date.
.NET Framework Defense in Depth Vulnerability This security update addresses an issue in AIA fetching process.
Quality and Reliability Improvements
|
ASP.NET |
- Addresses an issue with JavaScriptSerializer where after installing the January Security and Quality update there is a performance degradation. |
|
CLR1 |
- Addresses an issue with thread pool recycled lists become unresponsive on multi-CPU-group computers. - Addresses an issue where Interlocked.Read from 32-bit apps are much slower on some computers. |
|
Compiler |
- Addresses a problem using the native C# compiler (csc.exe) to compile code making calls to COM interop assemblies. |
1Common Language Runtime (CLR)
Known issues in this update
Microsoft is not currently aware of any issues in this update.
How to get this update
Install this update
|
Release Channel |
Available |
Next Step |
|
Windows Update and Microsoft Update |
No |
See note |
|
Windows Update for Business |
No |
See note |
|
Microsoft Update Catalog |
No |
See note |
|
Windows Server Update Services (WSUS) |
No |
See note |
Note: This update is no longer available. At this time, no functional issues have been reported with this update. To ensure your device continues to receive the latest security updates and quality improvements, we recommend installing the most recent cumulative update.
File information
For a list of the files that are provided in this update, download the file information for cumulative update.
Prerequisites
To apply this update, you must have .NET Framework 3.5 or 4.8.1 installed.
Restart requirement
You must restart the computer after you apply this update if any affected files are being used. We recommend that you exit all .NET Framework-based applications before you apply this update.
How to obtain help and support for this update
-
Help for installing updates: Windows Update FAQ
-
Protect yourself online and at home: Windows Security support
-
Local support according to your country: International Support
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