The September 2026 Security Update Review
ZDI's September 2026 Microsoft update review lists two already-exploited Windows EoP zero-days and dozens of critical RCEs across Office, SQL Server, and Windows services.
The review catalogs Microsoft's September 2026 fixes, marking CVE-2026-85880 (Windows ALPC) and CVE-2026-81963 (Windows Update Stack) as already exploited elevation-of-privilege issues. It also lists critical RCE flaws in Office, Word, Excel, PowerPoint, Outlook, SQL Server, Windows DNS, DHCP and Failover Cluster, plus graphics component RCEs. Azure-side fixes include Entra ID, Copilot Studio, Azure AI Language and Azure AD B2C elevation-of-privilege flaws.
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.
Hackers Abuse VSSAdmin to Extract NTDS.dit and Delete Windows Recovery Copies
Huntress details intruders using PsExec and VSSAdmin on domain controllers to steal NTDS.dit credentials and delete shadow copies before ransomware.
Huntress analysts identified attackers launching SYSTEM-level command shells via PsExec on a domain controller, then running 'vssadmin create shadow' to snapshot and copy the NTDS.dit Active Directory database. Shadow copies were later deleted to destroy local recovery options ahead of a likely ransomware stage. Huntress recommends correlating VSS creation/deletion events with remote execution, DNS enumeration, and lateral movement rather than alerting on any single VSS event.