KB5120705: Overview with user sentiment and feedback

Overview

KB5120705 is a cumulative security and reliability update for .NET Framework 3.5 and 4.8 released on August 11, 2026, targeting Windows Server 2022 systems. The update addresses six security vulnerabilities including elevation of privilege and remote code execution issues. This patch is recommended as part of regular maintenance routines for affected environments.

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)
• Fixes elevation of privilege vulnerabilities in .NET Framework
• Resolves remote code execution vulnerabilities affecting .NET applications
• Implements information disclosure vulnerability patches
• Provides cumulative reliability improvements for .NET Framework components

General Sentiment

This update addresses significant security concerns and is recommended by Microsoft for regular deployment. However, the patch introduces two documented issues affecting WPF applications, particularly those handling font rendering and XPS document processing. One issue has been resolved in subsequent updates, while the other remains under investigation. Organizations should carefully test this update in non-production environments before broad deployment.

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)
• WPF applications printing from in-memory XPS documents registered with PackageStore may fail with System.IO.FileFormatException when using pack scheme URIs (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 01:32 PM

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