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.NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 Security update
Patch Tuesday

KB5049625

KB5049625: Cumulative update for .NET Framework, versions 3.5 and 4.8.1, on Windows Server 2022, January 2025. Remote code execution flaw and rare CLR thread loop addressed

In short

The update addresses a .NET Framework remote code execution vulnerability and a rare issue that could cause an infinite loop when a thread first enters the CLR.

Does it affect you? Applies to: Windows Server 2022 devices with .NET Framework 3.5 or 4.8.1 installed.

File version
2.0.50727.9179 · 4.8.9294.0
Security
1 fixed
Restart
Required

What changes

Fixes 2 changes

.NET Framework

  • A remote code execution vulnerability in .NET Framework is addressed.1
    Addresses CVE-2025-21176.

.NET Runtime

  • In rare cases, a thread entering the CLR for the first time could cause an infinite loop; this issue is addressed.2

Technical details

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

Data sheet

Released
2025-01-14
Classification
Security Updates
Type
Cumulative update
Restart
Required
Replaces
KB5046264, KB5044035
Replaced by
KB5066134
VersionFile versionChannel
3.5 2.0.50727.9179 General availability
4.8.1 4.8.9294.0 General availability

Security

1 vulnerability fixed
1 not rated
VulnerabilitySeverityCVSS
CVE-2025-21176
.NET, .NET Framework, and Visual Studio Remote Code Execution Vulnerability
 Not rated —

Downloads (Microsoft Update Catalog)

x64 Windows Server 2022
72.1 MB
windows10.0-kb5049625-x64-ndp481.msu Main update · KB5049625 SHA-1: cced48b8…22c5b4

Updated components

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

Top changed componentsFiles
.NET runtime (CLR)12

Sources

Updated
Cited passages from Microsoft's official notes (2)
  1. 1. This security update addresses a remote code execution vulnerability detailed in CVE-2025-21176. support.microsoft.com
  2. 2. Addresses an issue where in rare cases where an infinite loop could occur when a thread enters CLR for the first time. support.microsoft.com
Checked automatically: 7 of 8 checks passed, 2 quoted passages · compared with Microsoft's page on Oct 20, 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 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