KB5134133OOBOut-of-band release · 2026-10 OOB

Out-of-band release for Windows 11, version 26H2 and 2 more versions

Support article Update Catalog CVEs in Security CVE list for a ticket

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It fixes actively exploited vulnerabilities. Deploy as soon as possible.

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Urgency Critical · 1 exploited Risk Low

Includes the security fixes of KB5127648
Fixes 1 exploited vulnerability; CISA deadline 16 Oct
Microsoft lists no open known issues from it or KB5127648
Released 2 days ago

Everything in the October 2026 Patch Tuesday cycle

Companion updates for this Windows version

Same patch cycle

Windows and .NET Framework are serviced separately. These packages target the same Windows version; choose the framework packages that apply to your installation.

KB5127690.NET Framework

.NET Framework 3.5 and 4.8.1Win 11 24H2 · Win 11 25H2 · Server 2025

13 Oct 2026

KB5127694.NET Framework

.NET Framework 3.5 and 4.8.1Win 11 26H2

13 Oct 2026

Companion updates do not replace this KB or establish an installation prerequisite.

3Windows versions

MSRC lists no CVEs under this KB itself; it includes the security fixes of KB5127648 (1009 CVEs). Windows release health lists no known issues from this update or the one it builds on, and none it resolves.

Applies to

From Microsoft's release-information tables

Servicing branch	OS build	Release	Available
Windows 11, version 26H2	26300.9725	OOB 2026-10 OOB	26 Oct 2026
Windows 11, version 25H2	26200.9725	OOB 2026-10 OOB	26 Oct 2026
Windows 11, version 24H2	26100.9725	OOB 2026-10 OOB	26 Oct 2026

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