Product

KB5124008

3 mentions in 7 days · 3 in 30 days · 3 total · first seen Sep 10, 2026 · last 4h ago

Timeline3 articles

Windows 11 KB5124008 Update Breaks Active Directory Domain Trust and Blocks User Logins

Microsoft's September Windows 11 cumulative update KB5124008 breaks Active Directory domain trust on domain-joined machines, blocking logins despite valid credentials.

Microsoft is investigating community reports that KB5124008, the September 8, 2026 cumulative update for Windows 11 24H2/25H2 (builds 26100.9445/26200.9445), breaks the AD secure channel, causing 'The user name or password is incorrect' errors on interactive logon. Admins reproduced the failure consistently and observed nltest error 1786 (ERROR_NO_TRUST_LSA_SECRET) plus domain controller Event 4625 with status 0xC000006D over NTLM. The problem is suspected in Machine Identity Isolation, a Credential Guard capability that moves machine-account secrets into virtualization-based security, and disabling it via registry value, Group Policy, or Intune baseline restored trust. The September 14 out-of-band update KB5129195 does not address the domain trust issue, and Microsoft's release notes do not list it as a known problem.

Cyber Security News00:29 UTC · 4h agoVulnerability 2 sources

Windows 11 KB5124008 update breaks domain trust for some users

Microsoft is investigating Windows 11 KB5124008 breaking Active Directory domain trust, leaving some users unable to log in with valid credentials.

Administrators report the Windows 11 KB5124008 security update breaks the secure channel between domain-joined machines and Active Directory, causing login failures on Windows 11 25H2 systems after reboot. The failures are linked to the Machine Identity Isolation feature, which in enforcement mode moves machine account secrets into Credential Guard and removes the LSA copy; one admin saw 11 of roughly 256 devices affected. Workarounds include setting MachineIdentityIsolation to 0 and repairing the secure channel with Test-ComputerSecureChannel, though Microsoft has confirmed no root cause or official fix and warns disabling the feature can also break domain authentication.

BleepingComputerupdated 00:29 UTC · 4h agofirst Sep 16, 20:39 UTC · 8h agoVulnerability 2 sources

Microsoft fixes bug that wiped Windows desktop settings

Microsoft's September 2026 Patch Tuesday (KB5124008) fixes a bug that reset desktop wallpapers and settings on Windows 11 24H2 and 25H2.

Microsoft said desktop settings failed to load after the optional KB5120998 August 2026 preview update on Windows 11 24H2 and 25H2, showing a solid black background and preventing restoration of customizations. The issue also changed or reset mouse settings and could install automatically when 'Get the latest updates as soon as they're available' is enabled. The KB5124008 cumulative update released September 8, 2026 resolves it; a similar wallpaper bug was fixed in February 2020 (KB4539602).

BleepingComputerupdated Sep 10, 11:14 UTC · 6d agofirst Sep 10, 08:08 UTC · 6d agoOther 2 sources1

Appears with

product Windows 11 3 vendor Microsoft 3 product Credential Guard 2 product Active Directory 2 product KB5120998 1 organization Microsoft 1 product KB5129195 1

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