At a glance: A previously patched critical Netlogon vulnerability is currently being actively exploited—administrators must apply the May patch package immediately.
A vulnerability in Windows Netlogon, which was already remedied in the May patch package, is currently being actively exploited by attackers. The vulnerability enables Remote Code Execution with elevated privileges.
Microsoft addressed the vulnerability in the Windows Netlogon service in the May patch package. The Netlogon service is central to authentication and authorization in Windows domains, which is why a vulnerability here can have significant implications for network security.
For CISOs, this active exploitation represents an immediate threat to infrastructure. Attackers exploiting this vulnerability can achieve Remote Code Execution with Domain Admin privileges and thereby directly compromise control systems and sensitive assets. The fact that patches are already available but attackers are actively targeting unpatched systems suggests a large-scale exploitation campaign.
Administrators should immediately verify whether Windows Server systems in their environment have applied the May patch package. Unpatched Domain Controllers and other critical server systems must be updated with the highest priority. In parallel, network monitoring and threat detection should be calibrated for anomalous Netlogon activity to detect exploitation attempts.
Source: www.heise.de · Published 1 June 2026
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