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KB5126655: Overview with user sentiment and feedback

Last Updated November 5, 2026

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Known Issues

Overview

KB5126655 is the October 13, 2026 cumulative security update for Windows Server 2022 (OS Build 20348.5761). It bundles the September 2026 non-security preview content and the out-of-band KB5129237, and it installs alongside servicing stack update KB5126654. It applies to Windows Server 2022 only. The input contained no separate known-issue summary field, so the known issues below come from Microsoft's KB page.

General Purpose

  • Adds enhanced NTLM auditing to help administrators find legacy NTLM dependencies.
  • Enables permanent DST for British Columbia and Alberta from November 2026 and adds the Manitoba Standard Time zone.
  • Upgrades bundled cURL to 8.21.0.
  • Adds ReFS auditing for externally attached storage. Auditing is on by default; enforcement is off.
  • Automatically remediates overly permissive AD FS DKM container ACLs (CVE-2026-56155). Opt-out via RemediateDkmAcl=0.
  • Fixes Storage Spaces Direct virtual disks staying offline after updates and some USB Audio Class 1.0 device failures.

General Sentiment

Community discussion is sparse, with one Tech Community thread from late October 2026 reporting that the update would not install and rolled back on a server. Another commenter describes a boot failure ("disk read error" after a second restart) on several Supermicro boards using Intel SATA RAID, and a second user reports the same. These are unverified anecdotal reports rather than confirmed Microsoft issues. The fixes themselves draw no direct complaints in the sources reviewed.

Known Issues

  • Exchange Server: some on-premises servers may fail OWA sign-in (MapiExceptionMdbOffline, Event ID 1006), stall mailbox replication, or leave outgoing mail in the Outbox; a registry workaround for the new Endpoint Mapper limit is documented.
  • WSUS does not display synchronization error details after KB5070884 or later (intentional, tied to CVE-2025-59287).

Disclaimer: We take measures to ensure that AI-generated content is of the highest possible quality, but we cannot guarantee its accuracy and recommend that users do their own independent research. Generated on 2026-11-05 07:29 AM

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