Microsoft Confirms KB5127648 Breaks Smart App Control, Shares Fix

Microsoft has confirmed that the October 2026 security update KB5127648 can prevent Windows 11 users from enabling Smart App Control, a security feature designed to block untrusted and potentially malicious applications.

According to Microsoft, the issue affects some devices running Windows 11 24H2, 25H2, and 26H2. On affected systems, the option to enable Smart App Control in Windows Security appears grayed out, preventing users from activating the feature.

However, devices that already have Smart App Control enabled remain unaffected and continue receiving protection.

Microsoft shares temporary workarounds

Microsoft has not released a permanent fix but has provided two workarounds for administrators managing affected Windows 11 devices.

The first involves creating two DWORD values in the Windows Registry by running these commands:

reg add "HKLM\SYSTEM\CurrentControlSet\Policies\Microsoft\FeatureManagement\Overrides" /v 2883193997 /t REG_DWORD /d 1 /f

reg add "HKLM\SYSTEM\CurrentControlSet\Policies\Microsoft\FeatureManagement\Overrides" /v 2850574478 /t REG_DWORD /d 1 /f

The changes require administrator privileges and a system restart to take effect.

Group Policy workaround also available

Microsoft has also released two Group Policy packages for affected Windows 11 versions:

• KB5074105 261015_19222 Feature Preview
• KB5074105 261015_19221 Feature Preview

Administrators must install both packages, enable the corresponding policies, and restart their devices. These policies restore the ability to enable Smart App Control and activate additional logging for troubleshooting.

This isn’t the only problem with Microsoft’s October updates. The company has also confirmed Wi-Fi and VPN connectivity issues affecting KB5127648 and KB5126646, while KB5127648 includes known issues involving Remote Desktop connections and USB audio.

Microsoft has not announced when it will release a permanent fix for the Smart App Control problem.

Via BleepingComputer