Windows · Patchstand
2026-09-08ReviewSecurity
Windows Server 2025 · KB5122871 · Build 26100.33438
KB5122871 updates Windows Server 2025 to OS build 26100.33438 in Microsoft's 8 September 2026 security release.
What changed
Microsoft published the 2026-09-08 security baseline for Windows Server 2025 with KB5122871 and build 26100.33438.
Technical details
- KB5122871 security update for Windows Server 2025
- OS build 26100.33438
Why it matters
The current Microsoft KB and OS build are the baseline for deployment rings, compliance and servicing reports.
Known limitations
- Review the linked Microsoft KB for current known issues, safeguards and resolved issues.
Now check
- Validate KB5122871 and build 26100.33438 in the pilot ring
- Review the Microsoft KB known-issue section
- Confirm servicing stack and update media prerequisites