Microsoft Support:
The February 10, 2026 update for Windows 11, version 26H1 includes security and cumulative reliability improvements in .NET Framework 4.8.1. We recommend that you apply this update as part of your regular maintenance routines. Before you install this update, see the Prerequisites and Restart requirement sections.
Summary
Security ImprovementsCVE-2025-55248 - .NET Framework Information Disclosure vulnerability
This security update addresses an information disclosure vulnerability detailed in CVE-2025-55248.
Quality and Reliability Improvements
| .NET Runtime | - Addresses an issue to update operating system calls for compliance with current standards. - Addresses an issue to add verification logic for ClickOnce to support SHA384 and SHA512. - Addresses an issue in cases where the arm64 CLR could crash when code generates and catches a NullReferenceException within the same function. |
Known issues in this update
Microsoft is not currently aware of any issues in this update.How to get this update
Install this update| Release Channel | Available | Next Step |
|---|---|---|
| Windows Update and Microsoft Update | Yes | None. This update will be downloaded and installed automatically from Windows Update. |
| Windows Update for Business | Yes | None. This update will be downloaded and installed automatically from Windows Update. |
| Microsoft Update Catalog | Yes | To get the standalone package for this update, go to the Microsoft Update Catalog website. |
| Windows Server Update Services (WSUS) | Yes | This update will automatically sync with WSUS if you configure as follows: Product: Windows 11, version 26H1 Classification: Security Updates |
File information
For a list of the files that are provided in this update, download the file information for cumulative update.
Prerequisites
To apply this update, you must have .NET Framework 4.8.1 installed.Restart requirement
You must restart the computer after you apply this update if any affected files are being used. We recommend that you exit all .NET Framework-based applications before you apply this update. Source:
