Microsoft has released Windows 11 Insider Preview Build 26300.7939 (KB5077243) to the Dev Channel, giving testers an early look at new security enhancements, audio improvements, and accessibility updates that are part of the upcoming version 25H2 development cycle.
As with other Dev Channel releases, features are being rolled out gradually using Controlled Feature Rollout (CFR), meaning not all Insiders will see every change right away.
Stronger Security for Batch Files and CMD Scripts
One of the standout additions in this build is a new security enhancement for batch file and Command Prompt script processing.
Microsoft is introducing an optional “more secure mode” designed to prevent scripts from being modified while they’re running. This improvement is aimed particularly at enterprise environments where code integrity policies are in place, helping reduce tampering risks while improving reliability under stricter security configurations.
Shared Audio Gets Smarter
Shared audio — a feature that allows two users to listen simultaneously using separate Bluetooth LE audio devices — receives meaningful refinements in this build.
Users can now:
- Adjust individual volume controls for each connected device
- See a new taskbar indicator when shared audio is active
Previously, volume adjustments affected both listeners. The new independent sliders provide a much more practical shared listening experience, especially useful in classrooms, travel scenarios, or collaborative environments.
Accessibility Improvements for Narrator
Accessibility continues to be a focus. Narrator now supports a new shortcut:
- Narrator key + \
This command reads status bar content in apps such as Microsoft Word, Excel, and PowerPoint, making it easier for screen reader users to quickly access contextual information without navigating away from their workflow.
Additional Fixes and Improvements
Build 26300.7939 also includes several reliability improvements:
- Taskbar: Ongoing refinements to autohide behavior, with certain animations temporarily paused to improve stability.
- Storage: Better cleanup reliability for update-related files.
- Input: Improved typing reliability for the ADLaM keyboard layout.
Dev Channel Reminder
Because this is a Dev Channel build, features may evolve, be modified, or never ship in a public release. The desktop watermark associated with Insider builds remains expected behavior.
Insiders who want to receive new features as soon as they’re available can enable the toggle under:
Settings → Windows Update → Get the latest updates as soon as they’re available
With security enhancements, improved shared audio controls, and accessibility refinements, Build 26300.7939 continues shaping the Windows 11 25H2 experience — even if some features are still experimental.
