CVE-2026-20874 is a race condition vulnerability classified under CWE-362, found in the Windows Management Services component of Microsoft Windows 10 Version 1809 (build 17763.0). The vulnerability arises due to improper synchronization when multiple threads or processes concurrently access shared resources, leading to a race condition. This flaw allows an attacker with authorized local access and low privileges to exploit the timing window to elevate their privileges on the affected system. The vulnerability impacts confidentiality, integrity, and availability, as an attacker could gain higher privileges and potentially execute arbitrary code or disrupt system operations. The CVSS v3.1 base score is 7.8, reflecting high severity with attack vector local, attack complexity high, privileges required low, and no user interaction needed. The scope is changed, indicating that the vulnerability affects resources beyond the initially vulnerable component. Currently, there are no known exploits in the wild, but the vulnerability is publicly disclosed and patched status is not indicated, suggesting the need for immediate patching once updates are available. This vulnerability is particularly critical because Windows Management Services is a core component, and exploitation could compromise system security significantly. The flaw is reserved since December 2025 and published in January 2026, indicating recent discovery and disclosure.

For European organizations, the impact of CVE-2026-20874 can be substantial, especially for those still operating Windows 10 Version 1809 in production environments. Successful exploitation allows attackers to escalate privileges locally, potentially leading to full system compromise, unauthorized access to sensitive data, disruption of critical services, and lateral movement within networks. This is particularly concerning for sectors with stringent data protection requirements such as finance, healthcare, and government agencies. The vulnerability could facilitate insider threats or post-compromise escalation by external attackers who have gained limited local access. Given the high confidentiality, integrity, and availability impact, organizations could face regulatory penalties under GDPR if breaches occur. Additionally, critical infrastructure operators relying on legacy Windows 10 versions may experience operational disruptions. The absence of known exploits in the wild currently reduces immediate risk but does not eliminate the threat, as attackers may develop exploits rapidly following public disclosure.

1. Apply official security patches from Microsoft immediately once they become available for Windows 10 Version 1809 to remediate the race condition. 2. If patching is delayed, restrict local access to affected systems by enforcing strict user account control policies and limiting administrative privileges. 3. Employ application whitelisting and endpoint detection and response (EDR) solutions to monitor for unusual local privilege escalation attempts. 4. Conduct thorough audits of systems running Windows 10 1809 to identify and upgrade or isolate legacy systems where feasible. 5. Implement robust logging and alerting for Windows Management Services activities to detect potential exploitation attempts. 6. Educate IT staff about the vulnerability and ensure rapid incident response capabilities are in place. 7. Consider network segmentation to limit the impact of any local compromise. 8. Review and harden local security policies and group policies to minimize attack surface related to local privilege escalation.