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

KB5127685

KB5127685: Cumulative update for .NET Framework, versions 3.5 and 4.8, on Windows 10 1809 and Windows Server 2019, October 2026. Closes a critical spoofing flaw and a disclosed security bypass

In short

Fixes 21 security flaws, including a critical spoofing flaw and a publicly disclosed .NET Framework security bypass. It applies to Windows 10 version 1809 and Windows Server 2019.

Does it affect you? Applies to: Devices running Windows 10 version 1809 or Windows Server 2019 with .NET Framework 3.5 or 4.8 installed.

File version
2.0.50727.9073 · 4.8.4811.0
Security
21 fixed · 1 critical
Restart
Required

What changes

Improvements 19 changes

.NET Framework

19 items
  • Blocks a flaw that could disrupt a service.1
    Addresses CVE-2026-58280, a denial of service vulnerability.
  • Blocks a flaw that could let someone gain higher access.2
    Addresses CVE-2026-69439, an elevation of privilege vulnerability.
  • Blocks a flaw that could disrupt a service.3
    Addresses CVE-2026-69651, a denial of service vulnerability.
  • Blocks a flaw that could let someone run harmful code.4
    Addresses CVE-2026-70007, a remote code execution vulnerability.
  • Blocks a flaw that could let someone run harmful code.5
    Addresses CVE-2026-70035, a remote code execution vulnerability.
  • Blocks a flaw that could let someone run harmful code.6
    Addresses CVE-2026-70174, a remote code execution vulnerability.
  • Blocks a flaw that could let someone run harmful code.7
    Addresses CVE-2026-83520, a remote code execution vulnerability.
  • Blocks a flaw that could disrupt a service.8
    Addresses CVE-2026-84008, a denial of service vulnerability.
  • Blocks a flaw that could let someone gain higher access.9
    Addresses CVE-2026-85363, an elevation of privilege vulnerability.
  • Blocks a flaw that could let someone run harmful code.10
    Addresses CVE-2026-87697, a remote code execution vulnerability.
  • Blocks a flaw that could let someone impersonate another party.11
    Addresses CVE-2026-96222, a spoofing vulnerability.
  • Blocks a flaw that could let someone run harmful code.12
    Addresses CVE-2026-96224, a remote code execution vulnerability.
  • Blocks a flaw that could disrupt a service.13
    Addresses CVE-2026-96233, a denial of service vulnerability.
  • Blocks a flaw that could disrupt a service.14
    Addresses CVE-2026-96958, a denial of service vulnerability.
  • Blocks a flaw that could disrupt a service.15
    Addresses CVE-2026-96959, a denial of service vulnerability.
  • Blocks a flaw that could disrupt a service.16
    Addresses CVE-2026-96960, a denial of service vulnerability.
  • Blocks a flaw that could expose information.17
    Addresses CVE-2026-97788, an information disclosure vulnerability.
  • Blocks a flaw that could let someone change data without permission.18
    Addresses CVE-2026-97801, a tampering vulnerability.
  • Blocks a flaw that could bypass a security check.19
    Addresses CVE-2026-108398, a security feature bypass vulnerability.

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
KB5126048, KB5120703
VersionFile versionChannel
3.5 2.0.50727.9073 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 2019 / Windows Server 2019
92.1 MB
windows10.0-kb5127685-x64-ndp48.msu Main update · KB5127685 SHA-1: bf787edd…3bd316
x86 Windows 10 Enterprise LTSC 2019
52.3 MB
windows10.0-kb5127685-x86-ndp48.msu Main update · KB5127685 SHA-1: a0d22924…9b7476

Updated components

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

Top changed componentsFiles
WPF28
WCF17
.NET runtime (CLR)14
ASP.NET6
.NET data access2
.NET networking2
Windows Forms2

Sources

Updated
Cited passages from Microsoft's official notes (19)
  1. 1. This security update addresses a denial of service vulnerability detailed in [CVE-2026-58280.] 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
Checked automatically: 7 of 8 checks passed, 19 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 4/5, 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