The Update BureauKB5036608: Cumulative update for .NET Framework, versions 3.5 and 4.8, on Windows 10 21H2/22H2, April 2024. Patches a remote code flaw and addresses unresponsive task queues
In short
The update addresses a remote code-execution flaw in .NET and two other security issues. It also tackles slowdowns in ASP.NET apps and background tasks that stop responding.
Does it affect you? Applies to: Devices running Windows 10, versions 21H2 or 22H2, with .NET Framework 3.5 or 4.8 installed. This includes Windows 10 Enterprise LTSC 2021.
Review notes Additional details from the official release notes (4) Read notes
- This page On computers with multiple CPU groups, the issue affected thread-pool recycled lists becoming unresponsive.
- In short On computers with multiple CPU groups, the issue affected thread-pool recycled lists becoming unresponsive.
- In detail On computers with multiple CPU groups, the issue affected thread-pool recycled lists becoming unresponsive.
- What changes On computers with multiple CPU groups, the issue affected thread-pool recycled lists becoming unresponsive.
The official sources are linked at the end of the page.
What changes
Fixes 5 changes
.NET Framework
3 items
-
A security flaw that could let an attacker run code on a device remotely is addressed.1
Addresses CVE-2024-21409, a .NET Framework remote code execution vulnerability.
-
A security issue involving an outdated component used by .NET is addressed.2
Addresses an issue where the version of the OSS zlib library is out of date.
-
A security issue in a .NET process that fetches information is addressed.3
Addresses an issue in the AIA fetching process.
ASP.NET
Verified in package
-
Some .NET apps could run more slowly after the January Security and Quality update; this update addresses the slowdown.4
Addresses the
JavaScriptSerializerperformance degradation after installing the January Security and Quality update.
CLR
-
On computers that use multiple groups of processors, background tasks could stop responding; this update addresses the issue.5
Addresses the issue in which thread pool recycled lists become unresponsive on multi-CPU-group computers.
Technical details
Data sheet · Security · Downloads · Components Click to collapse or expand
Data sheet
- Released
- 2024-04-09
- Classification
- Security Updates
- Type
- Cumulative update
- Restart
- Required
- Replaces
- KB5034468, KB5033909
- Replaced by
- KB5039884
| Version | File version | Channel |
|---|---|---|
| 3.5 | 2.0.50727.9176 | General availability |
| 4.8 | 4.8.4718.0 | General availability |
Security
| Vulnerability | Severity | CVSS |
|---|---|---|
|
.NET, .NET Framework, and Visual Studio Remote Code Execution Vulnerability
|
Not rated | — |
Downloads (Microsoft Update Catalog)
x64
Windows 10 Enterprise LTSC 2021 / Windows 10, version 22H2
70.9 MB
Arm64
Windows 10 Enterprise LTSC 2021 / Windows 10, version 22H2
45.3 MB
x86
Windows 10 Enterprise LTSC 2021 / Windows 10, version 22H2
45.3 MB
Updated components
148 files changed since the previous update for the same versions.
| Top changed components | Files |
|---|---|
| WPF | 45 |
| .NET runtime (CLR) | 18 |
| WCF | 18 |
| ASP.NET | 15 |
Verified in package: changed files confirm ASP.NET.
Sources
Updated
Cited passages from Microsoft's official notes (5)
-
1.
This security update addresses a remote code execution vulnerability detailed in CVE-2024-21409.
support.microsoft.com -
2.
This security update addresses an issue where version of the OSS zlib library is out of date.
support.microsoft.com -
3.
This security update addresses an issue in AIA fetching process.
support.microsoft.com -
4.
Addresses an issue with JavaScriptSerializer where after installing the January Security and Quality update there is a performance degradation.
support.microsoft.com -
5.
Addresses an issue with thread pool recycled lists become unresponsive on multi-CPU-group computers.
support.microsoft.com
Checked automatically: 7 of 8 checks passed, 5 quoted passages · compared with Microsoft's page on Oct 20, 2026
- Quotes found in the official pages: passed
- Numbers found in the sources: passed
- Vulnerabilities from the dossier only: passed
- Links to allowed domains only: passed
- Every official change covered: passed
- Readable plain text: passed
- Changes confirmed by the file list: passed
- Sources agree: not passed
A second AI read the text against the sources: correctness 4/5, clarity 4/5, completeness 5/5. How we work
Published by The Update Bureau. Written with AI from Microsoft's own documents, checked by rules and a second AI. How we work · Report a mistake