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

KB5126050

KB5126050: Cumulative update for .NET Framework, versions 3.5 and 4.8, on Windows Server 2022, September 2026. Privilege-escalation and code-execution flaws addressed

In short

The update addresses .NET Framework elevation-of-privilege and remote-code-execution vulnerabilities. Although the KB page still lists CVE-2026-62886, a later correction removed it from the vulnerability listing.

Does it affect you? Applies to: Windows Server 2022 devices with .NET Framework 3.5 or 4.8 installed. The update package is for x64.

File version
2.0.50727.9183 · 4.8.4806.0
Security
2 fixed
Restart
Required

What changes

Fixes 2 changes

.NET Framework

2 items

For: Windows Server administrators

  • The elevation-of-privilege vulnerability CVE-2026-62886 is addressed, according to the KB page.1
    The KB page says the update addresses the .NET Framework elevation-of-privilege vulnerability CVE-2026-62886. A later correction removed this CVE from the vulnerability listing.
  • The remote code execution vulnerability CVE-2026-69522 is addressed.2
    .NET Framework remote code execution vulnerability 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
KB5120705, KB5101010
Replaced by
KB5127687
VersionFile versionChannel
3.5 2.0.50727.9183 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 Server 2022
76.3 MB
windows10.0-kb5126050-x64-ndp48.msu Main update · KB5126050 SHA-1: 12dff491…1afa6c

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 4/5. 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