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KB5120708: Overview with user sentiment and feedback

Last Updated August 27, 2026

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Known Issues

Overview

KB5120708 is a cumulative security and reliability update for .NET Framework 3.5 and 4.8.1 released on August 11, 2026, targeting Windows 11 version 25H2 and Microsoft server operating system 24H2. This patch addresses six security vulnerabilities including elevation of privilege and remote code execution issues. The update is distributed automatically through Windows Update and is recommended as part of regular maintenance routines.

General Purpose

  • Addresses six critical security vulnerabilities (CVE-2026-65810, CVE-2026-62872, CVE-2026-62886, CVE-2026-62897, CVE-2026-70354, CVE-2026-62902)
  • Includes two elevation of privilege vulnerabilities and three remote code execution vulnerabilities
  • Provides one information disclosure vulnerability fix
  • Delivers cumulative reliability improvements to .NET Framework components
  • Automatically deployed via Windows Update for affected systems

General Sentiment

Community reception has been mixed due to significant functional regressions introduced by this update. While the security fixes are substantial and necessary, multiple reports indicate widespread printing and PDF/XPS generation failures in WPF applications, particularly affecting business-critical software. Users appreciate the security improvements but express frustration with the application compatibility issues and the need to apply workarounds that reduce security protections. The patch has generated considerable discussion on technical forums and gaming communities regarding crashes and UI rendering problems.

Known Issues

  • WPF applications fail with System.IO.FileFormatException when printing or generating PDF/XPS content using certain fonts, including Calibri
  • Affects document generation workflows in business applications relying on font subsetting
  • Some third-party applications like Covetrus ImproMed report blank dialog screens and rendering issues
  • Gaming applications (Arc Raiders) experience crashes related to the update
  • Status: Microsoft investigating with temporary workaround available

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 2026-08-27 01:20 PM

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