Microsoft has released the cumulative security update KB5124012 (Build 28000.2954) for Windows 11 version 26H1 as part of Patch Tuesday for September 2026. The update contains a number of improvements and fixes aimed at increasing the stability, security, and usability of the operating system. Special attention is paid to audio functions, compatibility with ARM64 devices, and the correct operation of system components.
- Voice Isolation. A feature has been added to suppress background noise during audio recording, which improves the quality of voice input and recording in noisy environments.
- Automatic volume leveling. Improvements have been made to ensure automatic leveling of sound volume for more comfortable perception.
- New sound controls. Additional sound controls have appeared in the Settings app, expanding audio configuration options.
- Stability of window transitions. Fixed issues where transitions between application windows could work inconsistently. Switching has now become smoother and more reliable.
- Mail and calendar synchronization. Resolved issues affecting data synchronization for mail and calendar.
- Faster File Explorer and clipboard. Improved performance of File Explorer and the clipboard, speeding up everyday file and text operations.
- Support for Myanmar Text and Mongolian Baiti fonts. Added support for these fonts, improving text rendering in the corresponding languages.
- Updated time zones. Updated time zone settings for Morocco, Israel, and Greenland. In particular, Morocco will switch to permanent UTC+00:00 time starting September 20, 2026.
- DHCP fixes. Resolved issues related to DHCP protocol operation.
- IPPS printing fixes. Resolved issues affecting printing via the IPPS protocol.
- Azure Virtual Desktop compatibility. Fixes have been made to improve compatibility with Azure Virtual Desktop.
- Secure Boot. Microsoft has expanded the list of devices that can automatically receive new Secure Boot certificates. Their distribution through the Windows Update service will continue in the coming months on supported consumer and unmanaged corporate PCs.
- Microsoft Teams and Outlook (ARM64). Fixed an issue where Microsoft Teams and Microsoft Outlook could unexpectedly terminate on computers with ARM64 architecture.
- Remote Desktop. Fixed an audio redirection issue where, in some configurations, sound from a remote session was not played on the local device.
- OMA-DM client. Diagnostic logging has been improved. Information about the certificate chain of server connections has been added, which will help administrators identify problems connecting devices to the management system.
To install update KB5124012, open Settings, go to Windows Update, and click Check for updates. The system will find and offer to install the cumulative update. A computer restart will be required to complete the installation.
The update can also be downloaded manually from the Microsoft Update Catalog if automatic installation is unavailable for any reason. Additionally, it is worth noting that the update includes all previously released fixes for Windows 11 version 26H1, so separate previous patches do not need to be installed after it.
| Feature / Change | Performance Impact | Optimization | PC Speed | Gaming Optimization |
|---|---|---|---|---|
| Voice Isolation | π’ High (improves voice input quality) | π’ High (background noise suppression) | βͺ No direct impact | π‘ Medium (cleaner voice chat in noisy environments) |
| Automatic volume leveling | βͺ No direct impact | π‘ Medium (consistent audio levels) | βͺ No impact | π‘ Medium (more comfortable game audio) |
| New sound controls | βͺ No impact | π‘ Medium (expanded configuration) | βͺ No impact | π‘ Low (custom audio setup) |
| Stability of window transitions | π’ Medium (smoother switching) | π’ Medium (reliable window management) | π‘ Low (less UI lag) | π‘ Low (alt-tab stability) |
| Mail and calendar synchronization | π‘ Low (fixed sync issues) | π’ Medium (reliable data sync) | βͺ No impact | βͺ Not applicable |
| Faster File Explorer and clipboard | π’ High (faster file operations) | π’ High (optimized explorer) | π’ High (quicker everyday tasks) | π‘ Low (faster file access) |
| Support for Myanmar Text and Mongolian Baiti fonts | βͺ No impact | π‘ Low (better text rendering) | βͺ No impact | βͺ Not applicable |
| Updated time zones | βͺ No impact | π‘ Low (correct time settings) | βͺ No impact | βͺ Not applicable |
| DHCP fixes | π‘ Medium (stable network connections) | π’ Medium (reliable IP assignment) | π‘ Low (faster network setup) | π‘ Low (stable online gaming connection) |
| IPPS printing fixes | π‘ Low (fixed printing issues) | π‘ Medium (reliable IPPS printing) | βͺ No impact | βͺ Not applicable |
| Azure Virtual Desktop compatibility | π‘ Medium (improved VDI performance) | π’ Medium (better AVD integration) | π‘ Low (smoother remote desktop) | π‘ Low (cloud gaming via AVD) |
| Secure Boot | βͺ No impact | π’ High (expanded certificate distribution) | π‘ Low (faster secure boot updates) | βͺ Not applicable |
| Microsoft Teams and Outlook (ARM64) | π’ Medium (fixed unexpected termination) | π’ Medium (stable ARM64 apps) | π‘ Low (no crashes) | βͺ Not applicable |
| Remote Desktop | π‘ Medium (fixed audio redirection) | π’ Medium (reliable remote audio) | βͺ No impact | π‘ Low (remote play audio) |
| OMA-DM client | βͺ No impact | π‘ Medium (improved diagnostic logging) | βͺ No impact | βͺ Not applicable |
Find and Change Settings
| Setting | Where to find | How to change |
|---|---|---|
| Voice Isolation | Settings > System > Sound > Input | Select your microphone and enable the "Voice Isolation" option to suppress background noise during recording. To disable it, return to the same location and turn the option off. |
| Automatic Volume Leveling | Settings > System > Sound > Output | Enable "Automatic volume leveling" to allow the system to adjust sound volume for more comfortable perception. Disable it in the same place if you prefer manual control. |
| New Sound Controls | Settings > System > Sound | Additional sound controls are available in the Sound section. Open Settings > System > Sound and explore the expanded options for configuring your audio devices. |
| Stability of Window Transitions | Settings > System > Multitasking | Improved window transition stability is applied automatically. You can adjust related behavior under Settings > System > Multitasking. |
| Mail and Calendar Synchronization | Settings > Accounts > Email & accounts | Synchronization issues are resolved automatically. To manage sync settings, go to Settings > Accounts > Email & accounts and select your account. |
| Faster File Explorer and Clipboard | Settings > System > Clipboard | Performance improvements are applied automatically. You can manage clipboard history under Settings > System > Clipboard. |
| Support for Myanmar Text and Mongolian Baiti Fonts | Settings > Personalization > Fonts | Font support is added automatically. You can view available fonts under Settings > Personalization > Fonts. |
| Updated Time Zones | Settings > Time & language > Date & time | Time zone updates are applied automatically. To manually change your time zone, go to Settings > Time & language > Date & time and select the appropriate option. |
| DHCP Fixes | Settings > Network & internet | DHCP issues are resolved automatically. To manage network settings, go to Settings > Network & internet and select your connection. |
| IPPS Printing Fixes | Settings > Bluetooth & devices > Printers & scanners | IPPS printing fixes are applied automatically. To manage printers, go to Settings > Bluetooth & devices > Printers & scanners. |
| Azure Virtual Desktop Compatibility | Settings > System > Remote Desktop | Compatibility fixes are applied automatically. To configure Remote Desktop, go to Settings > System > Remote Desktop. |
| Secure Boot | Settings > Windows Update > Advanced options | Secure Boot certificate distribution happens automatically through Windows Update. To check for updates, go to Settings > Windows Update. |
| Microsoft Teams and Outlook (ARM64) | Settings > Apps > Installed apps | The crash issue is fixed automatically. To manage app updates, go to Settings > Apps > Installed apps and check for updates. |
| Remote Desktop Audio Redirection | Settings > System > Remote Desktop | Audio redirection fix is applied automatically. To configure Remote Desktop audio, go to Settings > System > Remote Desktop and adjust audio settings. |
| OMA-DM Client | Settings > Accounts > Access work or school | Diagnostic logging improvements are applied automatically. To manage device management connections, go to Settings > Accounts > Access work or school. |
Official announcement on the Microsoft website.
The last 10 Windows updates:
| Update | Build | Version | Windows | Channel | Date |
|---|---|---|---|---|---|
| KB5124010 | 26300.9539 | 26H2 | Windows 11 | Preview | 2026-09-10 |
| KB5125726 | 28120.2912 | 26H1 | Windows 11 | Experimental | 2026-09-08 |
| KB5124058 | 26340.9354 | 26H2 | Windows 11 | Experimental | 2026-09-08 |
| KB5124061 | 26220.9343 | 25H2 | Windows 11 | Beta | 2026-09-08 |
| KB5124059 | 28020.2904 | 26H1 | Windows 11 | Beta | 2026-09-08 |
| KB5122880 | 22631.7582 | 23H2 | Windows 11 | Stable | 2026-09-08 |
| KB5122878 | 19045.7725 | 22H2 (ESU) | Windows 10 | Stable | 2026-09-08 |
| KB5124012 | 28000.2954 | 26H1 | Windows 11 | Stable | 2026-09-08 |
| KB5124008 | 26300.9445 | 26H2 | Windows 11 | Stable | 2026-09-08 |
| KB5121157 | 28020.2818 | 26H1 | Windows 11 | Beta | 2026-08-31 |