The Centre for Cybersecurity Belgium (CCB) has warned about the exploitation of a critical vulnerability in Windows Netlogon, identified as CVE-2026-41089, which allows remote code execution on domain controllers without prior access or authentication. This vulnerability, characterized as a stack-based buffer overflow, was patched by Microsoft during the May 2026 Patch Tuesday. The CCB emphasized the urgency of patching vulnerable servers, noting that the vulnerability is actively being exploited. The CVSS score for this vulnerability is 9.8. Further details on the ongoing attacks have not been disclosed, and Microsoft has not updated its advisory on the vulnerability.