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

KB5101004

KB5101004: Cumulative update for .NET Framework, versions 3.5 and 4.8.1, on Windows 11 23H2, July 2026. Remote code execution flaw addressed; secure request hangs improved

In short

The update addresses 17 Important vulnerabilities, including a remote code execution flaw, and two reliability issues involving hanging secure web requests and incorrect debugger reports.

Does it affect you? Applies to: Devices running Windows 11, version 23H2, with .NET Framework 3.5 or 4.8.1 installed. Packages are available for x64 and Arm64.

File version
2.0.50727.9182 · 4.8.9339.0
Security
17 fixed
Restart
Required

What changes

Fixes 2 changes

.NET Libraries

For: Applications using .NET

  • The update addresses cases where secure web requests could hang with certain server configurations.1
    Addresses hanging synchronous HttpWebRequest connections in specific secure connection scenarios.

.NET Runtime

For: Developers using the Visual Studio x86 debugger

  • The update addresses cases where certain floating-point values could be reported incorrectly while debugging.2
    Applies to the Visual Studio x86 native debugger during step operations in mixed-code applications.

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
KB5087058, KB5082424, KB5066133, KB5064403
+2 earlier KB5056580, KB5049624
Replaced by
KB5120713
VersionFile versionChannel
3.5 2.0.50727.9182 General availability
4.8.1 4.8.9339.0 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

Updated components

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

Top changed componentsFiles
WPF28
WCF14
.NET runtime (CLR)12
.NET networking6
.NET data access2

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 5/5, 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