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

KB5087066

KB5087066: Cumulative update for .NET Framework, versions 3.5 and 4.8, on Windows 10 1809 and Windows Server 2019, May 2026. Two privilege-escalation vulnerabilities addressed

In short

Addresses two .NET Framework elevation-of-privilege vulnerabilities. It applies to Windows 10, version 1809 and Windows Server 2019 devices with .NET Framework 3.5 or 4.8 installed.

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
2.0.50727.9068 · 4.8.4802.0
Security
2 fixed
Restart
Required

What changes

Fixes 2 changes

.NET Framework

2 items

For: devices with .NET Framework 3.5 or 4.8 installed

  • Addresses a vulnerability that could let an attacker gain higher privileges.1
    CVE-2026-32177: .NET Framework elevation of privilege vulnerability.
  • Addresses a vulnerability that could let an attacker gain higher privileges.2
    CVE-2026-35433: .NET Framework elevation of privilege vulnerability.

Technical details

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

Data sheet

Released
2026-05-12
Classification
Security Updates
Type
Cumulative update
Restart
Required
Replaces
KB5082414, KB5066137
Replaced by
KB5101008
VersionFile versionChannel
3.5 2.0.50727.9068 General availability
4.8 4.8.4802.0 General availability

Security

2 vulnerabilities fixed
2 important
VulnerabilitySeverityCVSS
CVE-2026-32177
.NET Elevation of Privilege Vulnerability
 Important 7.3
CVE-2026-35433
.NET Elevation of Privilege Vulnerability
 Important 7.3

Downloads (Microsoft Update Catalog)

x64 Windows Server 2019 / Windows 10 Enterprise LTSC 2019
89.3 MB
windows10.0-kb5087066-x64-ndp48.msu Main update · KB5087066 SHA-1: 086eed6e…48d5fd
x86 Windows 10 Enterprise LTSC 2019
50.8 MB
windows10.0-kb5087066-x86-ndp48.msu Main update · KB5087066 SHA-1: bfebf0dc…9b5ed1

Updated components

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

Top changed componentsFiles
WPF28

Sources

Updated
Cited passages from Microsoft's official notes (2)
  1. 1. This security update addresses a Elevation of Privilege vulnerability detailed in CVE-2026-32177. support.microsoft.com
  2. 2. This security update addresses a Elevation of Privilege vulnerability detailed in CVE-2026-35433. support.microsoft.com
Checked automatically: 8 of 8 checks passed, 2 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 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