KB5121650: Overview with user sentiment and feedback
Last Updated September 30, 2026
Probability of successful installation and continued operation of the machine
Overview
KB5121650 is a cumulative security and quality update for .NET Framework 3.5, 4.8, and 4.8.1 released on August 11, 2026, for Windows Server 2022. This patch addresses six security vulnerabilities including elevation of privilege and remote code execution issues affecting .NET Framework components. The update is distributed through Windows Update, Microsoft Update, and WSUS channels.
General Purpose
- Addresses CVE-2026-65810 and CVE-2026-62872 elevation of privilege vulnerabilities in .NET Framework
- Resolves three remote code execution vulnerabilities (CVE-2026-62886, CVE-2026-62897, CVE-2026-70354)
- Patches information disclosure vulnerability CVE-2026-62902
- Includes quality and reliability improvements for .NET Framework components
- Available through standard Windows Update channels for automatic deployment
General Sentiment
Limited community feedback is available for this patch, which is typical for infrastructure-focused .NET Framework updates. The patch addresses critical security vulnerabilities, making it a necessary security update. However, two documented known issues related to WPF applications and font handling have been identified, with one resolved in the September 2026 update and another still under investigation at the time of release.
Known Issues
- WPF applications may fail with System.IO.FileFormatException when printing or generating PDF/XPS content using certain fonts like Calibri (Resolved in September 2026 update; temporary workaround available via AppContext switch)
- WPF applications printing or displaying print preview from in-memory XPS documents registered with System.IO.Packaging.PackageStore may fail with System.IO.FileFormatException when using pack scheme URIs (Status: Investigating; workaround available via AppContext switch or code rebuild)
Disclaimer: We take measures to ensure that AI-generated content is of the highest possible quality, but we cannot guarantee its accuracy and recommend that users do their own independent research. Generated on 2026-09-30 07:42 AM
