Patch tracker / KB5129235

KB5129235: Windows Server Out-of-band update (September 2026)

KB5129235 is a non-security out-of-band update for Windows Server, released 2026-09-14, producing OS build 26100.33451. 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

26100.33451

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 thisread these before you deploy broadly

Microsoft documents 2 known issues with this update.

Windows Server Update Services (WSUS) does not display error details
USB Audio Class 1.0 devices with error Code 10 or no output

The full text, quoted from Microsoft

Microsoft Update Catalog: download KB5129235 Microsoft support article: what changed

Senserva AI Opinion and rich prompt for KB5129235

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 KB5129235 (source: https://senserva.com/kb/5129235.html, data from MSRC, CISA KEV, FIRST.org EPSS, NVD, refreshed twice a day (morning and afternoon US Central)):
- Update: KB5129235, 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=KB5129235
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 KB5129235 is installed

Elevated PowerShell. No output means it is not installed.

# Is KB5129235 installed? (elevated PowerShell)
Get-HotFix -Id KB5129235 -ErrorAction SilentlyContinue

# Across many machines (replace the names):
Invoke-Command -ComputerName SERVER01,SERVER02 {
  Get-HotFix -Id KB5129235 -ErrorAction SilentlyContinue
} | Select-Object PSComputerName, HotFixID, InstalledOn

Known issues, from Microsoft

Quoted from Microsoft's support article for KB5129235 (checked 2026-09-15). Verify against the article before acting.

Windows Server Update Services (WSUS) does not display error details

After installing KB5070881 or later updates, Windows Server Update Services (WSUS) does not display synchronization error details within its error reporting. This functionality is temporarily removed to address the Remote Code Execution Vulnerability, CVE-2025-59287 .

USB Audio Class 1.0 devices with error Code 10 or no output

Symptoms

After installing the September 8, 2026, Windows security update, some USB Audio Class 1.0 devices might fail to start or produce audio. Affected devices might experience one or more of the following symptoms:

The device displays an error in Device Manager: "This device cannot start (Code 10).”

No audio output.

Volume controls are unresponsive or remain at zero.

Sound settings are unresponsive or unavailable.

This issue is limited to USB Audio Class 1.0 devices.

Resolution

Microsoft is working on a resolution and will update this documentation when more information is available.

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 KB5129235 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.

KB5129235: Windows Server Out-of-band update (September 2026)

Update summary

Check if KB5129235 is installed

Known issues, from Microsoft

CVEs fixed by this update

Scope and sources

KB5122871

KB5122876

KB5122878

KB5122880

KB5122882

KB5123065

KB5123066

KB5123099