Note
- Release Date:
April 9, 2024 - Version:
.NET Framework 3.5 and 4.8.1
The April 9, 2024 update for Microsoft server operating system, 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This security update addresses an issue where version of the OSS zlib library is out of date.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 | Yes | None. This update will be downloaded and installed automatically from Windows Update. |
| Windows Update for Business | 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 as follows: Product: Microsoft server operating system, version 23H2 Classification: Security Updates |
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