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.NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 Security update
Patch Tuesday

KB5101002

KB5101002: Cumulative update for .NET Framework, versions 3.5 and 4.8.1, on Windows 11 26H1, July 2026. Fixes hanging HTTP requests and debugger value reports

In short

Addresses 17 .NET Framework security vulnerabilities and fixes two reliability issues, including HTTP requests that could hang in certain secure connection scenarios.

Does it affect you? Applies to: Windows 11, version 26H1 devices receiving .NET Framework 3.5 and 4.8.1 servicing. .NET Framework 4.8.1 must be installed; the available package is for Arm64.

File version
4.8.9340.0
Security
17 fixed
Restart
Required

What changes

Fixes 2 changes

.NET Libraries

For: Applications using synchronous HttpWebRequest connections

  • Some synchronous web requests no longer hang in the specified secure connection scenarios.1
    Addresses hanging synchronous HttpWebRequest connections with certain server configurations.

.NET Runtime

For: Visual Studio x86 debugger users

  • The Visual Studio x86 debugger reports certain floating-point values correctly while stepping through mixed-code applications.2
    Addresses incorrect floating-point values reported during step operations in the Visual Studio x86 native debugger.

Technical details

Data sheet · Security · Downloads · Components Click to collapse or expand

Data sheet

Released
2026-07-14
Classification
Security Updates
Type
Cumulative update
Restart
Required
Replaces
KB5092431, KB5087055, KB5082421, KB5074837
Replaced by
KB5120711
VersionFile versionChannel
3.5 General availability
4.8.1 4.8.9340.0 General availability

Security

17 vulnerabilities fixed
17 important
VulnerabilitySeverityCVSS
CVE-2026-47304
.NET Security Feature Bypass Vulnerability
 Important 8.1
CVE-2026-50646
.NET Framework Remote Code Execution Vulnerability
 Important 7.8
CVE-2026-50649
.NET Remote Code Execution Vulnerability
 Important 7.8
CVE-2026-50650
.NET Framework Elevation of Privilege Vulnerability
 Important 7.8
CVE-2026-47302
.NET Denial of Service Vulnerability
 Important 7.5
CVE-2026-50304
Windows Active Directory Federation Services Denial of Service Vulnerability
 Important 7.5
CVE-2026-50355
Windows Active Directory Federation Services Denial of Service Vulnerability
 Important 7.5
CVE-2026-50368
Windows Active Directory Federation Services Denial of Service Vulnerability
 Important 7.5
CVE-2026-50411
Windows Active Directory Federation Services Denial of Service Vulnerability
 Important 7.5
CVE-2026-50525
.NET Denial of Service Vulnerability
 Important 7.5
CVE-2026-50527
.NET Framework Denial of Service Vulnerability
 Important 7.5
CVE-2026-50647
Active Directory Federation Server Denial of Service Vulnerability
 Important 7.5
CVE-2026-50648
.NET Framework Denial of Service Vulnerability
 Important 7.5
CVE-2026-50652
Azure Active Directory Denial of Service Vulnerability
 Important 7.5
CVE-2026-50653
Azure Active Directory Denial of Service Vulnerability
 Important 7.5
CVE-2026-50659
.NET Spoofing Vulnerability
 Important 6.5
CVE-2026-50324
Windows Active Directory Federation Services Denial of Service Vulnerability
 Important 5.9

Downloads (Microsoft Update Catalog)

Arm64 Windows 11, version 26H1
56.5 MB
windows11.0-kb5101002-arm64-ndp481.msu Main update · KB5101002 SHA-1: 7ddf9490…67c7f3

Updated components

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

Top changed componentsFiles
WPF36
.NET runtime (CLR)18
WCF18
.NET networking9
.NET data access3

Sources

Updated
Cited passages from Microsoft's official notes (2)
  1. 1. Addresses an issue with synchronous HttpWebRequest connections where requests could hang in specific secure connection scenarios with certain server configurations. support.microsoft.com
  2. 2. Addresses an issue in the Visual Studio x86 native debugger where certain floating-point values could be reported incorrectly during step operations in mixed-code applications. support.microsoft.com
Checked automatically: 7 of 8 checks passed, 2 quoted passages · compared with Microsoft's page on Sep 25, 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 5/5, 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