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.NET Framework 3.5 / 4.8 .NET Framework 3.5 / 4.8 Security update
Patch Tuesday

KB5127683

KB5127683: Cumulative update for .NET Framework, versions 3.5 and 4.8, on Windows 10 21H2/22H2, October 2026. Critical .NET spoofing flaw addressed

In short

CVE-2026-96222 is a critical .NET Framework spoofing flaw addressed by this update. It also addresses the publicly disclosed security-feature bypass CVE-2026-108398.

Does it affect you? Applies to: Devices running Windows 10, version 21H2 or 22H2, including Windows 10 Enterprise LTSC 2021, with .NET Framework 3.5 or 4.8 installed.

File version
2.0.50727.9188 · 4.8.4811.0
Security
21 fixed · 1 critical
Restart
Required
Review notes Additional details from the official release notes (1) Read note
  • In detail CVE-2026-62886 was added to the update’s vulnerability information on November 8, after the October 13 release. The available sources do not establish that this update addresses it.

The official sources are linked at the end of the page.

What changes

Fixes 20 changes

.NET Framework

20 items
  • A .NET Framework denial-of-service flaw is addressed (CVE-2026-58280).1
    The update addresses CVE-2026-58280, a denial of service vulnerability.
  • A .NET Framework elevation-of-privilege flaw is addressed (CVE-2026-69439).2
    The update addresses CVE-2026-69439, an elevation of privilege vulnerability.
  • A .NET Framework denial-of-service flaw is addressed (CVE-2026-69651).3
    The update addresses CVE-2026-69651, a denial of service vulnerability.
  • A .NET Framework remote-code-execution flaw is addressed (CVE-2026-70007).4
    The update addresses CVE-2026-70007, a remote code execution vulnerability.
  • A .NET Framework remote-code-execution flaw is addressed (CVE-2026-70035).5
    The update addresses CVE-2026-70035, a remote code execution vulnerability.
  • A .NET Framework remote-code-execution flaw is addressed (CVE-2026-70174).6
    The update addresses CVE-2026-70174, a remote code execution vulnerability.
  • A .NET Framework remote-code-execution flaw is addressed (CVE-2026-83520).7
    The update addresses CVE-2026-83520, a remote code execution vulnerability.
  • A .NET Framework denial-of-service flaw is addressed (CVE-2026-84008).8
    The update addresses CVE-2026-84008, a denial of service vulnerability.
  • A .NET Framework elevation-of-privilege flaw is addressed (CVE-2026-85363).9
    The update addresses CVE-2026-85363, an elevation of privilege vulnerability.
  • A .NET Framework remote-code-execution flaw is addressed (CVE-2026-87697).10
    The update addresses CVE-2026-87697, a remote code execution vulnerability.
  • A critical .NET Framework spoofing flaw is addressed (CVE-2026-96222).11
    The update addresses CVE-2026-96222, a spoofing vulnerability. The dossier rates it Critical.
  • A .NET Framework remote-code-execution flaw is addressed (CVE-2026-96224).12
    The update addresses CVE-2026-96224, a remote code execution vulnerability.
  • A .NET Framework denial-of-service flaw is addressed (CVE-2026-96233).13
    The update addresses CVE-2026-96233, a denial of service vulnerability.
  • A .NET Framework denial-of-service flaw is addressed (CVE-2026-96958).14
    The update addresses CVE-2026-96958, a denial of service vulnerability.
  • A .NET Framework denial-of-service flaw is addressed (CVE-2026-96959).15
    The update addresses CVE-2026-96959, a denial of service vulnerability.
  • A .NET Framework denial-of-service flaw is addressed (CVE-2026-96960).16
    The update addresses CVE-2026-96960, a denial of service vulnerability.
  • A .NET Framework information-disclosure flaw is addressed (CVE-2026-97788).17
    The update addresses CVE-2026-97788, an information disclosure vulnerability.
  • A .NET Framework tampering flaw is addressed (CVE-2026-97801).18
    The update addresses CVE-2026-97801, a tampering vulnerability.
  • A publicly disclosed .NET Framework security-feature-bypass flaw is addressed (CVE-2026-108398).19
    The update addresses CVE-2026-108398, a security feature bypass vulnerability.
  • An Important .NET Framework vulnerability, CVE-2026-62886, was added to the update’s vulnerability information.20
    The dossier records CVE-2026-62886 as added after release and rated Important.

Technical details

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

Data sheet

Released
2026-10-13
Classification
Security Updates
Type
Cumulative update
Restart
Required
Replaces
KB5126046, KB5120701
VersionFile versionChannel
3.5 2.0.50727.9188 General availability
4.8 4.8.4811.0 General availability

Security

21 vulnerabilities fixed
1 critical 18 important 2 not rated
VulnerabilitySeverityCVSS
CVE-2026-96222
Active Directory Federation Services (AD FS) Spoofing Vulnerability
 Critical 7.4
CVE-2026-102869
.NET and Visual Studio Elevation of Privilege Vulnerability
 Important 8.8
CVE-2026-108398
.NET Framework Security Feature Bypass Vulnerability
 Important 8.8
CVE-2026-70007
.NET Framework Remote Code Execution Vulnerability
 Important 8.8
CVE-2026-70035
.NET Framework Remote Code Execution Vulnerability
 Important 8.8
CVE-2026-70174
.NET Remote Code Execution Vulnerability
 Important 8.8
CVE-2026-83520
.NET Remote Code Execution Vulnerability
 Important 8.8
CVE-2026-85363
.NET Framework Elevation of Privilege Vulnerability
 Important 8.8
CVE-2026-96224
.NET Remote Code Execution Vulnerability
 Important 8.8
CVE-2026-62886
.NET Elevation of Privilege Vulnerability
 Important 7.8
CVE-2026-58280
.NET Denial of Service Vulnerability
 Important 7.5
CVE-2026-69651
.NET Denial of Service Vulnerability
 Important 7.5
CVE-2026-84008
.NET Denial of Service Vulnerability
 Important 7.5
CVE-2026-96233
ASP.NET Core Denial of Service Vulnerability
 Important 7.5
CVE-2026-96958
.NET Denial of Service Vulnerability
 Important 7.5
CVE-2026-96959
.NET Denial of Service Vulnerability
 Important 7.5
CVE-2026-96960
.NET Denial of Service Vulnerability
 Important 7.5
CVE-2026-97788
Active Directory Federation Services (AD FS) Information Disclosure Vulnerability
 Important 7.5
CVE-2026-97801
.NET Framework Tampering Vulnerability
 Important 7.5
CVE-2026-69439
.NET and Visual Studio Elevation of Privilege Vulnerability
 Not rated —
CVE-2026-87697
.NET Remote Code Execution Vulnerability
 Not rated —

Downloads (Microsoft Update Catalog)

x64 Windows 10 Enterprise LTSC 2021 / Windows 10, version 22H2
78.2 MB
windows10.0-kb5127683-x64-ndp48.msu Main update · KB5127683 SHA-1: 708bc29a…6f9d1a
Arm64 Windows 10 Enterprise LTSC 2021 / Windows 10, version 22H2
49.5 MB
windows10.0-kb5127683-arm64-ndp48.msu Main update · KB5127683 SHA-1: f2005811…a5f4a4
x86 Windows 10 Enterprise LTSC 2021 / Windows 10, version 22H2
49.5 MB
windows10.0-kb5127683-x86-ndp48.msu Main update · KB5127683 SHA-1: afa79447…459f94

Updated components

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

Top changed componentsFiles
WPF42
WCF24
.NET runtime (CLR)21
ASP.NET9
.NET data access3
.NET networking3
Windows Forms3

Page history

  1. Added CVE-2026-62886 (Important)

Sources

Updated
Cited passages from Microsoft's official notes (20)
  1. 1. This security update addresses a denial of service vulnerability detailed in [CVE-2026-58280.] support.microsoft.com
  2. 2. This security update addresses an elevation of privilege vulnerability detailed in [CVE-2026-69439.] support.microsoft.com
  3. 3. This security update addresses a denial of service vulnerability detailed in [CVE-2026-69651.] support.microsoft.com
  4. 4. This security update addresses a remote code execution vulnerability detailed in [CVE-2026-70007.] support.microsoft.com
  5. 5. This security update addresses a remote code execution vulnerability detailed in [CVE-2026-70035.] support.microsoft.com
  6. 6. This security update addresses a remote code execution vulnerability detailed in [CVE-2026-70174.] support.microsoft.com
  7. 7. This security update addresses a remote code execution vulnerability detailed in [CVE-2026-83520.] support.microsoft.com
  8. 8. This security update addresses a denial of service vulnerability detailed in [CVE-2026-84008.] support.microsoft.com
  9. 9. This security update addresses an elevation of privilege vulnerability detailed in [CVE-2026-85363.] support.microsoft.com
  10. 10. This security update addresses a remote code execution vulnerability detailed in [CVE-2026-87697.] support.microsoft.com
  11. 11. This security update addresses a spoofing vulnerability detailed in [CVE-2026-96222.] support.microsoft.com
  12. 12. This security update addresses a remote code execution vulnerability detailed in [CVE-2026-96224.] support.microsoft.com
  13. 13. This security update addresses a denial of service vulnerability detailed in [CVE-2026-96233.] support.microsoft.com
  14. 14. This security update addresses a denial of service vulnerability detailed in [CVE-2026-96958.] support.microsoft.com
  15. 15. This security update addresses a denial of service vulnerability detailed in [CVE-2026-96959.] support.microsoft.com
  16. 16. This security update addresses a denial of service vulnerability detailed in [CVE-2026-96960.] support.microsoft.com
  17. 17. This security update addresses an information disclosure vulnerability detailed in [CVE-2026-97788.] support.microsoft.com
  18. 18. This security update addresses a tampering vulnerability detailed in [CVE-2026-97801.] support.microsoft.com
  19. 19. This security update addresses a security feature bypass vulnerability detailed in [CVE-2026-108398.] support.microsoft.com
  20. 20. The October 13, 2026 update for Windows 10 Version 21H2 and Windows 10 Version 22H2 includes security and cumulative reliability improvements in .NET Framework 3.5 and 4.8. support.microsoft.com
Checked automatically: 7 of 8 checks passed, 20 quoted passages · compared with Microsoft's page on Nov 14, 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 3/5, clarity 3/5, 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