Some Windows 11 enterprise PCs are losing their connection to company login systems after installing Microsoft’s KB5124008 security update, causing valid domain users to be locked out. Reports point to Windows 11 25H2 systems where the Machine Identity Isolation setting is switched to enforcement mode, breaking the secure channel with Active Directory after reboot. Microsoft says it is investigating; admins report a workaround of setting MachineIdentityIsolation to 0 and repairing the computer secure channel.
Why it matters: Organizations using domain-joined Windows 11 systems could face login outages after a routine security update, so this is operationally urgent even without a CVE. IT teams should test KB5124008 carefully, watch for broken domain trust after reboot, and be ready to apply the reported workaround or pause broader rollout.
Sergiu Gatlan
2026.09.17
97% relevant
This article advances the same event by adding Microsoft's official confirmation that September 2026 updates trigger the issue through Machine Identity Isolation enforcement, and by providing a temporary workaround to restore domain logins until a future fix arrives.
Lawrence Abrams
2026.09.16
100% relevant
This article establishes a new story about a specific Microsoft Windows 11 security update, KB5124008, causing domain trust failures on enterprise systems and prompting investigation and workarounds.
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