Threat Intelligence & APT BleepingComputer 1 month ago

Microsoft: KB5120998 mouse reset bug affects only non-English PCs

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CyberNew Threat Research Desk
• Original Reporting: BleepingComputer
CyberNew Threat Intel Assessment
Assessed Severity: INFORMATIONAL
Impacted Surface
Client Endpoints & Operating Systems
Intelligence Sector
Threat Intelligence & APT

Analyst Takeaway

"Microsoft says a known issue that reverts mouse settings after installing the KB5120998 August 2026 preview update affects only non-English Windows 11 systems. The bug was confirmed Friday , one day after the KB5120998 release , which includes Start menu, taskbar, and Windows search improvements for devices running Windows 11 versions 25H2 and 24H2. According to user reports, mouse cursor..."

Recommended Defense & Mitigation

  • Threat Monitoring: Ingest published IOCs into SIEM/EDR detection rules for continuous telemetry monitoring.
  • Security Awareness: Alert staff and maintain baseline endpoint hardening across endpoints.
Curated & Verified by CyberNew Threat Intelligence Desk Standard Defense Framework (NIST / MITRE ATT&CK)

Windows 11

Microsoft says a known issue that reverts mouse settings after installing the KB5120998 August 2026 preview update affects only non-English Windows 11 systems.

The bug was confirmed Friday, one day after the KB5120998 release, which includes Start menu, taskbar, and Windows search improvements for devices running Windows 11 versions 25H2 and 24H2.

According to user reports, mouse cursor personalization settings are changing or resetting automatically after installing the KB5120998 update, and affected Windows 11 users cannot restore their previous mouse settings after they are reverted.

"Following installation of Windows updates released August 27 2026 (KB5120998) and later, mouse personalization settings are being reverted to certain standard settings," Microsoft explained at the time.

"This includes cursor and cursor animations that are selected in the Mouse Properties options under Windows."

Only non-English Windows devices affected

In a Tuesday update to the Windows release health dashboard, the company noted that a follow-up investigation revealed the issue affects only non-English devices.

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Source Verification & Original Intelligence

This threat report was reviewed by CyberNew analysts and cross-referenced with primary security disclosures from BleepingComputer.

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