KB5124008: Overview with user sentiment and feedback

Overview

KB5124008 is a September 8, 2026 out-of-band-style security cumulative update for Windows 11 24H2 and 25H2 (OS Builds 26100.9445 and 26200.9445). It bundles a servicing stack update (KB5124007) and includes fixes for Secure Boot targeting, mouse cursor, personalization, Arm64 Teams/Outlook crashes, Morocco time zone, and RDP audio redirection. Microsoft lists several known issues in the update.

General Purpose

• Security fixes plus additional Secure Boot certificate device-targeting data
• Fixes black desktop background, customized mouse cursor display, and Teams/Outlook crashes on Arm64 PCs
• Updates Morocco Standard Time to permanent UTC+00:00 effective September 20, 2026
• Fixes Remote Desktop audio redirection failures in certain configurations
• Improves OMA-DM client diagnostic logging
• Includes AI component updates (Copilot+ PCs only)

General Sentiment

Community reception is strongly negative: a widely upvoted Reddit thread reports audio loss, Explorer crashes, Remote Desktop problems, and wallpaper or system tray issues, with some users rolling back or hiding the update. Some commenters note that many complaints lack reproduction details and that not all users are affected. Microsoft's own known-issues list is also substantial, so caution is warranted.

Known Issues

• Domain-joined devices with Credential Guard/Machine Identity Isolation may lose domain trust (resolved in KB5124010 per Microsoft's October 7, 2026 change log)
• USB Audio Class 1.0 devices may fail to start or produce no sound (partially fixed by OOB KB5129195; other symptoms still being worked on)
• Host folder shares may be unavailable in Hyper-V Linux VMs using Plan9 (resolved in KB5129195)
• Remote Desktop Services may stop responding (resolved in KB5129195)
• File History may fail to create or update backups (resolved in KB5124010)

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 2026-10-24 07:31 AM

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