CVE-2023-36405 is a high-severity elevation of privilege vulnerability affecting Microsoft Windows 10 Version 1809 (build 10.0.17763.0). The root cause is a race condition (CWE-362) in the Windows kernel, where concurrent execution using a shared resource occurs without proper synchronization. This flaw allows an attacker with limited privileges (low privilege) to exploit the timing window in the kernel's handling of shared resources, potentially enabling them to execute arbitrary code with elevated privileges. The vulnerability does not require user interaction but does require local access with some privileges. The CVSS 3.1 base score is 7.0, reflecting high impact on confidentiality, integrity, and availability (all rated high), but with a higher attack complexity and requiring local privileges. No known exploits are currently reported in the wild, and no official patches or mitigation links have been published at the time of analysis. The vulnerability could be leveraged by attackers to bypass security boundaries, escalate privileges, and gain control over affected systems, which could lead to full system compromise or persistent malware installation.

For European organizations, this vulnerability poses a significant risk especially to enterprises and government agencies still running Windows 10 Version 1809, which is an older but still in-use OS version in some sectors. Successful exploitation could allow attackers to escalate privileges from a low-privileged user account to SYSTEM level, enabling them to disable security controls, access sensitive data, or deploy ransomware and other malware. Critical infrastructure, financial institutions, and public sector entities could be targeted due to the potential for full system compromise. The vulnerability's requirement for local access limits remote exploitation but insider threats or malware that gains initial foothold could leverage this flaw to deepen system control. The lack of known exploits currently reduces immediate risk but also means organizations should proactively patch or mitigate to prevent future exploitation. The impact on confidentiality, integrity, and availability is high, making this a critical concern for maintaining secure operations and compliance with data protection regulations such as GDPR.

1. Upgrade or patch: Organizations should prioritize upgrading affected systems to a newer Windows 10 version or later, as Windows 10 Version 1809 is out of mainstream support and no official patch is currently available. 2. Restrict local access: Limit user accounts with local login privileges on critical systems to reduce the attack surface. 3. Implement application whitelisting and endpoint protection to detect and block suspicious privilege escalation attempts. 4. Monitor system logs and kernel events for unusual behavior indicative of race condition exploitation or privilege escalation. 5. Employ least privilege principles, ensuring users operate with minimal necessary permissions. 6. Use virtualization-based security features (e.g., Credential Guard) where possible to mitigate kernel-level attacks. 7. Prepare incident response plans to quickly address potential exploitation attempts. 8. Regularly audit and inventory systems to identify those running the vulnerable OS version and prioritize remediation accordingly.