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

KB5101000

KB5101000: Cumulative update for .NET Framework, versions 3.5 and 4.8.1, on Windows 10 21H2/22H2, July 2026. 17 .NET flaws addressed; secure web requests and debugger improved

In short

The update addresses 17 important .NET Framework security flaws, including one that could let an attacker run code. It also addresses hanging secure web requests and incorrect debugger values.

Does it affect you? Applies to: Devices running Windows 10 versions 21H2 or 22H2 with .NET Framework 3.5 or 4.8.1 installed.

File version
2.0.50727.9182 · 4.8.9339.0
Security
17 fixed
Restart
Required

What changes

Fixes 19 changes

.NET Framework

17 items
  • A flaw that could disrupt a service is addressed.1
    CVE-2026-47302: denial-of-service vulnerability.
  • A flaw that could bypass a security check is addressed.2
    CVE-2026-47304: security feature bypass vulnerability.
  • A flaw that could disrupt a service is addressed.3
    CVE-2026-50304: denial-of-service vulnerability.
  • A flaw that could disrupt a service is addressed.4
    CVE-2026-50324: denial-of-service vulnerability.
  • A flaw that could disrupt a service is addressed.5
    CVE-2026-50355: denial-of-service vulnerability.
  • A flaw that could disrupt a service is addressed.6
    CVE-2026-50368: denial-of-service vulnerability.
  • A flaw that could disrupt a service is addressed.7
    CVE-2026-50411: denial-of-service vulnerability.
  • A flaw that could disrupt a service is addressed.8
    CVE-2026-50525: denial-of-service vulnerability.
  • A flaw that could disrupt a service is addressed.9
    CVE-2026-50527: denial-of-service vulnerability.
  • A flaw that could give an attacker more access is addressed.10
    CVE-2026-50646: elevation of privilege vulnerability.
  • A flaw that could disrupt a service is addressed.11
    CVE-2026-50647: denial-of-service vulnerability.
  • A flaw that could disrupt a service is addressed.12
    CVE-2026-50648: denial-of-service vulnerability.
  • A flaw that could let an attacker run code is addressed.13
    CVE-2026-50649: remote code execution vulnerability.
  • A flaw that could give an attacker more access is addressed.14
    CVE-2026-50650: elevation of privilege vulnerability.
  • A flaw that could disrupt a service is addressed.15
    CVE-2026-50652: denial-of-service vulnerability.
  • A flaw that could disrupt a service is addressed.16
    CVE-2026-50653: denial-of-service vulnerability.
  • A flaw that could let an attacker alter data is addressed.17
    CVE-2026-50659: tampering vulnerability.

.NET Libraries

  • Some secure web requests that use HttpWebRequest no longer hang in the situations described.18
    Addresses synchronous HttpWebRequest connections that could hang in specific secure connection scenarios with certain server configurations.

.NET Runtime

For: Visual Studio x86 debugger users

  • The Visual Studio x86 debugger reports some floating-point values more accurately when stepping through mixed-code apps.19
    Addresses incorrect reporting of certain floating-point values during step operations in mixed-code applications 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
KB5087053, KB5082419
Replaced by
KB5120709
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

Downloads (Microsoft Update Catalog)

x64 Windows 10 Enterprise LTSC 2021 / Windows 10, version 22H2
77.5 MB
windows10.0-kb5101000-x64-ndp481.msu Main update · KB5101000 SHA-1: d2b329b2…c86ade
x86 Windows 10 Enterprise LTSC 2021 / Windows 10, version 22H2
48.9 MB
windows10.0-kb5101000-x86-ndp481.msu Main update · KB5101000 SHA-1: ab569aad…f080cc

Updated components

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

Top changed componentsFiles
WPF42
WCF21
.NET runtime (CLR)18
.NET networking9
.NET data access3

Sources

Updated
Cited passages from Microsoft's official notes (19)
  1. 1. This security update addresses a denial of service vulnerability detailed in CVE-2026-47302. support.microsoft.com
  2. 2. This security update addresses a security feature bypass vulnerability detailed in CVE-2026-47304. support.microsoft.com
  3. 3. This security update addresses a denial of service vulnerability detailed in CVE-2026-50304. support.microsoft.com
  4. 4. This security update addresses a denial of service vulnerability detailed in CVE-2026-50324. support.microsoft.com
  5. 5. This security update addresses a denial of service vulnerability detailed in CVE-2026-50355. support.microsoft.com
  6. 6. This security update addresses a denial of service vulnerability detailed in CVE-2026-50368. support.microsoft.com
  7. 7. This security update addresses a denial of service vulnerability detailed in CVE-2026-50411. support.microsoft.com
  8. 8. This security update addresses a denial of service vulnerability detailed in CVE-2026-50525. support.microsoft.com
  9. 9. This security update addresses a denial of service vulnerability detailed in CVE-2026-50527. support.microsoft.com
  10. 10. This security update addresses an elevation of privilege vulnerability detailed in CVE-2026-50646. support.microsoft.com
  11. 11. This security update addresses a denial of service vulnerability detailed in CVE-2026-50647. support.microsoft.com
  12. 12. This security update addresses a denial of service vulnerability detailed in CVE-2026-50648. support.microsoft.com
  13. 13. This security update addresses a remote code execution vulnerability detailed in CVE-2026-50649. support.microsoft.com
  14. 14. This security update addresses an elevation of privilege vulnerability detailed in CVE-2026-50650. support.microsoft.com
  15. 15. This security update addresses a denial of service vulnerability detailed in CVE-2026-50652. support.microsoft.com
  16. 16. This security update addresses a denial of service vulnerability detailed in CVE-2026-50653. support.microsoft.com
  17. 17. This security update addresses a tampering vulnerability detailed in CVE-2026-50659. support.microsoft.com
  18. 18. Addresses an issue with synchronous HttpWebRequest connections where requests could hang in specific secure connection scenarios with certain server configurations. support.microsoft.com
  19. 19. 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: 8 of 8 checks passed, 19 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: 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