The Update BureauKB5049615: Cumulative update for .NET Framework, versions 3.5 and 4.8, on Windows 10 1809 and Windows Server 2019, January 2025. Remote code execution flaw addressed; rare CLR loop fixed
In short
The update addresses CVE-2025-21176, 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: Devices running Windows 10, version 1809, or Windows Server 2019 with .NET Framework 3.5 or 4.8 installed.
What changes
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
- KB5046269, KB5044022
- Replaced by
- KB5066137
| Version | File version | Channel |
|---|---|---|
| 3.5 | 2.0.50727.9066 | General availability |
| 4.8 | 4.8.4775.0 | General availability |
Security
| Vulnerability | Severity | CVSS |
|---|---|---|
|
.NET, .NET Framework, and Visual Studio Remote Code Execution Vulnerability
|
Not rated | — |
Downloads (Microsoft Update Catalog)
x64
Windows 10 Enterprise LTSC 2019 / Windows Server 2019
88.9 MB
x86
Windows 10 Enterprise LTSC 2019
50.3 MB
Updated components
19 files changed since the previous update for the same versions.
| Top changed components | Files |
|---|---|
| .NET runtime (CLR) | 12 |
Sources
Updated
Cited passages from Microsoft's official notes (2)
-
1.
This security update addresses a remote code execution vulnerability detailed in CVE-2025-21176.
support.microsoft.com -
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 21, 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 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