Windows Server 2016 · KB5123099 · Build 14393.9512

What changed

Microsoft published the 2026-09-08 security baseline for Windows Server 2016 with KB5123099 and build 14393.9512.

Technical details

• KB5123099 security update for Windows Server 2016
• OS build 14393.9512

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 KB5123099 and build 14393.9512 in the pilot ring
• Review the Microsoft KB known-issue section
• Confirm servicing stack and update media prerequisites