KB5120698: Overview with user sentiment and feedback
Last Updated September 26, 2026
Probability of successful installation and continued operation of the machine
Overview
Released on August 11, 2026, this cumulative update addresses security and reliability improvements for .NET Framework 3.5 and 4.7.2 on Windows 10 version 1809 and Windows Server 2019. The patch resolves six critical vulnerabilities including elevation of privilege and remote code execution issues. This is a recommended security update as part of regular maintenance routines.
General Purpose
- Addresses six security vulnerabilities: CVE-2026-65810 and CVE-2026-62872 (elevation of privilege), CVE-2026-62886, CVE-2026-62897, and CVE-2026-70354 (remote code execution), and CVE-2026-62902 (information disclosure)
- Implements enhanced security protections for WPF font handling and XPS package boundary restrictions
- Provides cumulative reliability improvements for .NET Framework components
- No new quality improvements listed beyond security fixes
General Sentiment
This patch addresses significant security vulnerabilities and is officially recommended by Microsoft for regular deployment. However, the update introduces two known issues affecting WPF applications that handle fonts and XPS documents, which may impact legacy applications. Microsoft has provided workarounds for both issues, though these temporarily disable the new security protections. The second issue remains under investigation as of the publication date.
Known Issues
- WPF applications may fail with System.IO.FileFormatException when printing or generating PDF/XPS content using certain fonts (including Calibri); resolved in September 2026 update
- WPF applications that print or display print preview from in-memory XPS documents registered with System.IO.Packaging.PackageStore may fail with System.IO.FileFormatException; status is under investigation
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 2026-09-26 01:50 AM
