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KB5120703: Overview with user sentiment and feedback

Last Updated September 30, 2026

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Known Issues

Overview

KB5120703 is an August 11, 2026 cumulative security and reliability update for .NET Framework 3.5 and 4.8 targeting Windows 10 version 1809 and Windows Server 2019. This patch addresses six critical security vulnerabilities including multiple remote code execution and elevation of privilege issues. The update is recommended as part of regular maintenance routines for affected systems.

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 CVE-2026-62902 information disclosure vulnerability
  • Includes cumulative reliability improvements for .NET Framework components
  • Requires system restart after installation and .NET Framework 3.5 or 4.8 prerequisite

General Sentiment

The patch addresses significant security concerns with multiple critical vulnerabilities, which is positive for system security posture. However, the update introduces functional regressions affecting WPF applications, particularly those involving printing and PDF/XPS generation with specific fonts. Microsoft has acknowledged these issues and provided temporary workarounds, though users report the workarounds require disabling security protections, creating a trade-off between functionality and security.

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 printing or displaying print preview from in-memory XPS documents may fail with System.IO.FileFormatException when using pack scheme package identities; status investigating

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 PM

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