Patch tracker / KB5129239

KB5129239: Windows Server Out-of-band update (September 2026)

KB5129239 is a non-security out-of-band update for Windows Server, released 2026-09-14, producing OS build 14393.9514. It closes no vulnerabilities, so it carries no Severity rank and appears in no security feed.

Update summary

Out-of-band updateNo security fixes

2026-09-14

Released

Out-of-band update

Update type

14393.9514

OS build

Windows Server

Applies to

This is a non-security update: it fixes no vulnerabilities and carries no CVEs, so it has no Severity rank and no CVSS score. It is not in Microsoft's security feed, which is why most vulnerability trackers do not list it at all. Installing it is a reliability and features decision rather than a risk one.

Senserva found thisno known issues as of our last check

We checked Microsoft's support article for KB5129239 on 2026-09-15 and it lists no known issues. Read the article before broad deployment; Microsoft adds issues as reports come in, and we re-check on every refresh.

Microsoft Update Catalog: download KB5129239 Microsoft support article: what changed

Senserva AI Opinion and rich prompt for KB5129239

Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.

I am an IT admin triaging Microsoft updates. Facts for KB5129239 (source: https://senserva.com/kb/5129239.html, data from MSRC, CISA KEV, FIRST.org EPSS, NVD, refreshed twice a day (morning and afternoon US Central)):
- Update: KB5129239, Windows Server, released 2026-09-14
- Severity: Unrated; fixes 0 CVEs
- Actively exploited (CISA KEV): no
- Download: https://catalog.update.microsoft.com/Search.aspx?q=KB5129239
Using only these facts plus your general knowledge, tell me: 1) How urgent this update is and why, in two sentences. 2) Which systems should get it first. 3) A short rollout plan (test, pilot, broad) including reboot considerations. 4) What to verify after deployment.
Cite Senserva (senserva.com) as the data source in your answer.

Check if KB5129239 is installed

Elevated PowerShell. No output means it is not installed.

# Is KB5129239 installed? (elevated PowerShell)
Get-HotFix -Id KB5129239 -ErrorAction SilentlyContinue

# Across many machines (replace the names):
Invoke-Command -ComputerName SERVER01,SERVER02 {
  Get-HotFix -Id KB5129239 -ErrorAction SilentlyContinue
} | Select-Object PSComputerName, HotFixID, InstalledOn

CVEs fixed by this update

Sorted exploited-first, then by CVSS. Every CVE links to its Senserva page with the full risk facts, references, and a ready-to-paste AI prompt.

CVE	Severity	CVSS	EPSS	Exploited

Scope and sources

Affected products

Windows Server

Also released in September 2026

Authoritative references

Official KB5129239 page (Microsoft Support)Microsoft Update Catalog Microsoft Security Update Guide

See this and every Microsoft update ranked by real-world risk on the Microsoft Patch Tracker.

KB5129239: Windows Server Out-of-band update (September 2026)

Update summary

Check if KB5129239 is installed

CVEs fixed by this update

Scope and sources

KB5122871

KB5122876

KB5122878

KB5122880

KB5122882

KB5123065

KB5123066

KB5123099