Patch tracker / KB5124010
KB5124010: Windows 11 Optional preview update (September 2026)
KB5124010 is a non-security optional preview update for Windows 11, released 2026-09-29, producing OS build 26300.9550, 26200.9550. It closes no vulnerabilities, so it carries no Severity rank and appears in no security feed.
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Update summary
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 AI Opinion and rich prompt for KB5124010
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Check if KB5124010 is installed
Elevated PowerShell. No output means it is not installed.
Windows release health for this update
From Microsoft's Windows release health for Windows 11, version 25H2; Windows 11, version 24H2, checked 2026-10-25. Microsoft's issue text is linked from each title.
Issues Microsoft traces to this update
- Applications which require AC-3 audio decoding might close unexpectedly
Resolved by KB5127648. Microsoft last updated it 2026-10-13 10:13 PT. - Remote Desktop connections might fail for non-admin users with error 0xC000000D
Mitigated. Microsoft last updated it 2026-10-13 10:13 PT.
Issues this update resolves
- Domain-joined devices might lose their secure trust relationship with the domain
Resolved. Microsoft last updated it 2026-10-08 17:44 PT.
From the Senserva blog
- Open This Week: Windows 11 Known Issues and an Ivanti Zero-Day
October 18, 2026 · Mark Shavlik
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
- Also released in September 2026
KB5122871
684 CVEs · Critical · exploitedKB5122876
620 CVEs · Critical · exploitedKB5122878
572 CVEs · Critical · exploitedKB5122880
608 CVEs · Critical · exploitedKB5122882
645 CVEs · Critical · exploitedKB5123065
398 CVEs · Critical · exploitedKB5123066
423 CVEs · Critical · exploitedKB5123099
559 CVEs · Critical · exploitedThe full month, summarized: Microsoft Patch Tuesday.
- Authoritative references
See this and every Microsoft update ranked by real-world risk on the Microsoft Patch Tracker.