KB5120998DOptional non-security preview · 2026-08 D

Optional non-security preview for Windows 11, version 25H2 and Windows 11, version 24H2

Is it safe to deploy?

SupersededKB5120998D

Deploy KB5129195 instead; it includes these fixes.

UrgencyCritical · 1 exploited RiskModerate · 1 mitigated

2Windows versions

0CVEs fixed · 0 critical

0Exploited or in CISA KEV

1Open known issues affecting it

—Restart required (per MSRC)

From Microsoft's release-information tables

Servicing branch	OS build	Release	Available
Windows 11, version 25H2	26200.9278	D 2026-08 D	27 Aug 2026
Windows 11, version 24H2	26100.9278	D 2026-08 D	27 Aug 2026

Windows release health

Mitigatedfrom KB5120998Win 11 25H2, Win 11 24H2updated 24 Sep

Devices might experience a black screen or desktop loading issues after sign-inMicrosoft has received reports of this issue occurring in some virtual desktop environments.
Resolvedfrom KB5120998 fixed by KB5124008Win 11 25H2, Win 11 24H2updated 8 Sep

Mouse customization is reset on non-English Windows devicesCustom cursors and cursor animations may intermittently revert
Resolvedfrom KB5120998 fixed by KB5124008Win 11 25H2, Win 11 24H2updated 8 Sep

Desktop background settings are lost or reset on some devicesFor affected Windows installations, backgrounds might revert to a black solid color

Windows release health names no issues fixed by this KB.

1 news and community post · 1 report problems

Windows Born's Tech and Windows WorldKB5120998

28 Aug 2026

0 Microsoft CVEs · most urgent first

MSRC lists no CVEs for this KB in the collected releases; preview (D) and out-of-band updates often carry no new security fixes.