Microsoft has released KB5120998, an optional preview cumulative update for Windows 11 versions 25H2 and 24H2, according to BleepingComputer. The update includes 35 changes and fixes, with visible adjustments to the Start menu, taskbar, and Windows search. Because KB5120998 is a preview release, it is not the same as a standard monthly security cumulative update. BleepingComputer reports that the package is meant to let IT administrators test Windows bug fixes, quality improvements, and new features before those changes are expected to reach broader deployment in next month’s Patch Tuesday release. The update does not include security fixes. The most user-facing changes are in the taskbar and Start menu. After installing the August 2026 preview update, users can place the taskbar at the bottom, top, left, or right side of the screen through Windows Settings. BleepingComputer reports that most customization settings, including the option to never combine taskbar icons, work across those positions. Microsoft is also adding a smaller taskbar option that reduces taskbar height and icon size, a change aimed at preserving space on smaller devices. The update adds small and large Start menu size options, along with controls to independently show or hide Pinned, Recommended, and All sections. Users can also hide the account name and profile picture. KB5120998 also begins rolling out administrator protection, a security-hardening feature that lets users perform administrator tasks using just-in-time privileges. According to BleepingComputer, Microsoft describes the feature as profile separation intended to reduce exposure to elevation-of-privilege attacks, while also saying it is not a formal security boundary. The feature is off by default and can be enabled through Microsoft Intune using Open Mobile Alliance Uniform Resource Identifier settings or through Group Policy. The update can be installed through Windows Update by checking for updates and selecting the optional download and install link, unless the device is already configured to receive the latest updates as soon as they are available. BleepingComputer also notes that the update is available through the Microsoft Update Catalog for manual installation. Once installed, the update moves Windows 11 25H2 devices to build 26200.9278 and Windows 11 24H2 devices to build 26100.9278. Microsoft has also warned that a limited number of consumer and business systems may experience one additional restart during installation over recent and upcoming Windows updates, tied to the Secure Boot certificate update process. BleepingComputer separately notes that Microsoft recently reminded customers that Windows 11 24H2 Home and Pro editions are due to stop receiving updates in two months, while Enterprise and Education editions remain under mainstream support until October 2027. Who benefits: IT administrators get an early test window before next month’s Patch Tuesday deployment. Users on smaller devices may benefit from the reduced taskbar size and additional Start menu controls. Who's exposed: Organizations that delay testing may encounter user-interface changes or extra restart behavior later in the normal update cycle. Windows 11 24H2 Home and Pro users also face a nearer support deadline, according to BleepingComputer’s reporting on Microsoft’s reminder.