KB5129194: September 2026 out-of-band update for Windows 11, version 26H1

Windows Build Decoder: What a Windows build number means: 10.0.26100.2314 is Windows 11 24H2 with the November 2024 update. Version, KB, support dates, updates behind.

Paste a Windows build number from winver, ver, a system inventory or a vulnerability scan: 10.0.26100.2314, 19045.5487, Microsoft Windows [Version 10.0.22631.4460], a KB number or a version like 22H2. You get the Windows version (the same build is often a client and a server release), the cumulative update it has, how many monthly security updates behind it is, and how long that version gets updates. Versions, updates and dates come from Microsoft's release information for Windows 11, Windows 10 and Windows Server, read 2026-10-29.