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

KB5126048

KB5126048: Cumulative update for .NET Framework, versions 3.5 and 4.8, on Windows 10 1809 and Windows Server 2019, September 2026. Elevation-of-privilege and remote-code flaws addressed

In short

The update addresses two .NET Framework security vulnerabilities, including remote code execution and elevation of privilege. It applies to Windows 10 version 1809 and Windows Server 2019 systems with .NET Framework 3.5 or 4.8.

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
2.0.50727.9070 · 4.8.4806.0
Security
2 fixed
Restart
Required

What changes

Fixes 2 changes

.NET Framework

2 items
  • Addresses an elevation-of-privilege vulnerability.1
    CVE-2026-62886.
  • Addresses a remote code execution vulnerability.2
    CVE-2026-69522.

Technical details

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

Data sheet

Released
2026-09-08
Classification
Security Updates
Type
Cumulative update
Restart
Required
Replaces
KB5120703, KB5101008
Replaced by
KB5127685
VersionFile versionChannel
3.5 2.0.50727.9070 General availability
4.8 4.8.4806.0 General availability

Security

2 vulnerabilities fixed
1 important 1 not rated
VulnerabilitySeverityCVSS
CVE-2026-69522
.NET and Visual Studio Remote Code Execution Vulnerability
 Important 8.8
CVE-2026-62886
.NET Elevation of Privilege Vulnerability
 Not rated —

Downloads (Microsoft Update Catalog)

x64 Windows 10 Enterprise LTSC 2019 / Windows Server 2019
91.8 MB
windows10.0-kb5126048-x64-ndp48.msu Main update · KB5126048 SHA-1: 0795656f…8ba66e
x86 Windows 10 Enterprise LTSC 2019
52.2 MB
windows10.0-kb5126048-x86-ndp48.msu Main update · KB5126048 SHA-1: ac875819…4955d2

Updated components

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

Top changed componentsFiles
WPF22

Sources

Updated
Cited passages from Microsoft's official notes (2)
  1. 1. This security update addresses an elevation of privilege vulnerability detailed in CVE-2026-62886. support.microsoft.com
  2. 2. This security update addresses a remote code execution vulnerability detailed in CVE-2026-69522. support.microsoft.com
Checked automatically: 7 of 8 checks passed, 2 quoted passages · compared with Microsoft's page on Nov 8, 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