KB5127648 is a Microsoft update from Patch Tuesday October 2026, released on 13 Oct 2026. According to the Security Update Guide it fixes 877 vulnerabilities (Windows). Affected according to our entries: Microsoft Windows 11 25H2 with printers shared from Windows Server, Microsoft Windows 11 24H2 and later, Microsoft Windows 11 24H2/25H2, Microsoft Windows 11 File History. Known issues with this update: 4 open, 1 with workaround, 4 fixed.
Users report that adding a shared printer from a Windows Server via Settings > Add device fails with error 87 on Windows 11 25H2 after update KB5127648. This is reported by users, not yet confirmed by the vendor. Only one independent source has been found so far.
Microsoft · Windows 11 25H2 with printers shared from Windows Server
After installing KB5127648, Smart App Control can reportedly no longer be turned on. This is reported by users and news sites, not yet confirmed by the vendor in the sources available to us. No fix is known yet.
Microsoft · Windows 11 24H2 and later
Users report various problems after installing the KB5124010 preview update for Windows 11 24H2/25H2: slow boot, shutdown and search, a boot failure after uninstalling, and games crashing. These are reported by users, not yet confirmed by the vendor. Only 2 independent sources were found. A separate AC-3 (Dolby Digital) app crash is mentioned as resolved by KB5127648 according to the research notes.
Microsoft · Windows 11 24H2/25H2
Users report that File History copies files to the target drive, but the "Last copied on" date does not update and Previous Versions shows no entries. This is reported by users, not yet confirmed by the vendor. A related September 2026 File History bug was reportedly resolved by Microsoft, but no vendor source confirms the remaining problem.
Microsoft · Windows 11 File History
After installing KB5127648, Windows 11 clients reportedly fail to authenticate on WPA2-Enterprise Wi-Fi and wired 802.1X networks using PEAP (Protected Extensible Authentication Protocol). This is reported by users, not yet confirmed by the vendor. A likely cause, inferred and not listed by Microsoft, is that NTLMv1 single sign-on is now blocked by default. Reported mitigations exist, but no vendor fix is known.
Microsoft · Windows 11 24H2, 25H2, 26H2
Always On VPN profiles with automatic protocol selection or fallback (IKEv2 and SSTP) failed after the September 2026 Windows 11 updates. According to secondary sources and research notes, the optional preview update KB5127936 (28 Oct 2026) fixes this. We could not read the vendor page ourselves, so the details are not yet confirmed by a vendor source here.
Microsoft · Windows 11
After the Windows updates of September 22, 2026 (KB5124010) and later, some applications that need to decode AC-3 (Dolby Digital) audio might close unexpectedly. Microsoft has resolved the issue with the updates released October 13, 2026 (KB5127648) and later.
Microsoft · Windows 11, Version 26H2
After installing Windows 11, version 26H2 and subsequent updates, some devices may fail to load the desktop after sign-in. The issue was mainly observed on Azure Virtual Desktop (AVD) hosts using FSLogix, more often with some existing user profiles. Microsoft resolved it with the updates released on 2026-10-13 (KB5127648) and later.
Microsoft · Windows 11, Version 26H2
The October 2026 Windows security update was released on 2026-10-13 for all supported Windows versions. For Windows 11, version 26H2, it fixes several known problems: Always On VPN, a black screen in Azure Virtual Desktop with FSLogix, and tiered Storage Spaces Direct virtual disks. A limited number of devices may need one additional restart during installation because of the Secure Boot certificate update.
Microsoft · Windows 11
We continuously read the vendors’ official sources, community reports and trade media and summarise them in our own words, with a link to the source:
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We check whether your systems are affected, apply workarounds properly and plan for dated changes in good time.
