Microsoft has confirmed that the KB5120998 August 2026 non-security preview update for Windows 11 resets mouse settings on affected systems. The confirmation, reported by BleepingComputer on August 31, 2026, follows user reports of the issue after installing the update.
The update is a non-security preview, meaning it is optional and not part of the regular Patch Tuesday release. Users who have installed it may find that their mouse settings, such as pointer speed, button configuration, or other customizations, have been reverted to defaults.
A preview update with a side effect
KB5120998 is part of Microsoft's monthly preview update cycle, which allows users to test fixes and improvements before they are included in the next cumulative update. However, this particular preview appears to introduce a regression rather than a fix.
Microsoft has not yet provided details on the scope of the issue, such as which specific mouse settings are affected or whether all Windows 11 configurations are impacted. The company has also not announced a timeline for a resolution.
What users should consider
For users who have already installed KB5120998 and experienced the mouse settings reset, the immediate step is to reconfigure their mouse settings manually. Those who have not yet installed the update may choose to postpone it until Microsoft addresses the problem.
As a preview update, KB5120998 is not automatically deployed, giving users control over whether to apply it. Microsoft's confirmation is the first official acknowledgment of the issue, but the company has not yet stated when a fix will be available.
The open question remains: when will Microsoft release a corrective update, and will it be part of the next cumulative update or a standalone fix?