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.NET Framework 4.8 .NET Framework 4.8 Security update
Patch Tuesday

KB5036609

KB5036609: Cumulative update for .NET Framework, version 4.8, on Windows 10 1607 and Windows Server 2016, April 2024. Remote code execution flaw and ASP.NET slowdown addressed

In short

Addresses one Important .NET Framework remote code execution vulnerability (CVE-2024-21409) and reliability issues in ASP.NET and the CLR.

Does it affect you? Applies to: Devices running Windows 10, version 1607, or Windows Server 2016 with .NET Framework 4.8 installed.

File version
4.8.4718.0
Security
1 fixed
Restart
Required

What changes

Fixes 3 changes

.NET Framework

For: devices with .NET Framework 4.8

  • A remote code execution vulnerability in .NET Framework is addressed.1
    CVE-2024-21409.

ASP.NET

Verified in package

For: ASP.NET applications

  • Performance degradation in JavaScriptSerializer after the January Security and Quality update is addressed.2

CLR

For: computers with multiple CPU groups

  • An issue that can make thread pool recycled lists unresponsive on multi-CPU-group computers is addressed.3
    CLR means Common Language Runtime.

Improvements 2 changes

.NET Framework

2 items

For: devices with .NET Framework 4.8

  • An issue involving an outdated OSS zlib library is addressed as a defense-in-depth improvement.4
  • An issue in the AIA fetching process is addressed as a defense-in-depth improvement.5

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
KB5034614, KB5033910
Replaced by
KB5039885
VersionFile versionChannel
4.8 4.8.4718.0 General availability

Security

1 vulnerability fixed
1 important
VulnerabilitySeverityCVSS
CVE-2024-21409
.NET, .NET Framework, and Visual Studio Remote Code Execution Vulnerability
 Important 7.3

Downloads (Microsoft Update Catalog)

x64 Windows 10 Enterprise LTSB 2016 / Windows Server 2016
56.5 MB
windows10.0-kb5036609-x64-ndp48.msu Main update · KB5036609 SHA-1: 087fa1e6…9cf1cf
x86 Windows 10 Enterprise LTSB 2016
32.4 MB
windows10.0-kb5036609-x86-ndp48.msu Main update · KB5036609 SHA-1: 21d1b27b…187a31

Updated components

89 files changed since the previous update for the same versions.

Top changed componentsFiles
WPF22
.NET runtime (CLR)12
WCF12
ASP.NET10

Verified in package: changed files confirm ASP.NET.

Sources

Updated
Cited passages from Microsoft's official notes (5)
  1. 1. This security update addresses a remote code execution vulnerability detailed in CVE-2024-21409. support.microsoft.com
  2. 2. Addresses an issue with JavaScriptSerializer where after installing the January Security and Quality update there is a performance degradation. support.microsoft.com
  3. 3. Addresses an issue with thread pool recycled lists become unresponsive on multi-CPU-group computers. support.microsoft.com
  4. 4. This security update addresses an issue where version of the OSS zlib library is out of date. support.microsoft.com
  5. 5. This security update addresses an issue in AIA fetching process. 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