Critical Windows Netlogon Vulnerability (CVE-2026-41089) Under Active Exploitation

A critical vulnerability, CVE-2026-41089, affecting the Windows Netlogon service has been actively exploited. Patched by Microsoft during the May 2026 Patch Tuesday, the vulnerability allows unauthenticated attackers to execute remote code on vulnerable domain controllers. This stack-based buffer overflow in the Netlogon RPC interface poses a significant risk, potentially granting attackers full control of an Active Directory environment. The Centre for Cybersecurity Belgium has reported ongoing exploitation attempts against unpatched systems. Organizations are urged to apply the May 2026 security updates immediately and monitor for unusual activity. The vulnerability primarily affects enterprise networks with internet-facing domain controllers. Threat hunting and log reviews are recommended to detect signs of exploitation. Current protective measures include FortiGuard's IPS and antivirus services.

Key Points: • CVE-2026-41089 is a critical vulnerability in the Windows Netlogon service. • Active exploitation is reported, targeting unpatched domain controllers. • Immediate patching and monitoring are essential to mitigate risks.