CVE-2025-55224 is a race condition vulnerability classified under CWE-362 affecting the Windows 10 Version 1809 Win32K graphics subsystem (GRFX). The vulnerability arises from improper synchronization when multiple threads concurrently access shared resources, leading to a race condition. This flaw can be exploited by an authorized local attacker with low privileges to execute arbitrary code with elevated privileges. The vulnerability impacts the confidentiality, integrity, and availability of the affected system, as successful exploitation could allow an attacker to run malicious code, potentially leading to full system compromise. The CVSS 3.1 score of 7.8 reflects a high severity, with attack vector local (AV:L), attack complexity high (AC:H), privileges required low (PR:L), no user interaction (UI:N), and scope changed (S:C). The vulnerability was reserved on August 11, 2025, and published on September 9, 2025. No patches or known exploits are currently available, increasing the urgency for proactive mitigation. The flaw specifically affects Windows 10 Version 1809 build 10.0.17763.0, a version still in use in some enterprise environments. The race condition in the Win32K subsystem can be leveraged to execute code locally, which could be a stepping stone for privilege escalation or persistence by attackers.

For European organizations, this vulnerability poses a significant risk, especially for those still running Windows 10 Version 1809 in enterprise or critical infrastructure environments. Exploitation could lead to unauthorized code execution, resulting in data breaches, system downtime, or disruption of services. The compromise of confidentiality, integrity, and availability could affect sensitive data and critical operations, particularly in sectors such as finance, healthcare, government, and manufacturing. Since the attack requires local access but only low privileges, insider threats or attackers who gain initial foothold through other means could escalate their control. The lack of patches and known exploits means organizations must act proactively to prevent exploitation. The vulnerability could also be leveraged in targeted attacks against high-value European targets, increasing the threat landscape complexity.

Given the absence of patches, European organizations should implement strict access controls to limit local access to systems running Windows 10 Version 1809. Employing application whitelisting and endpoint detection and response (EDR) solutions can help detect suspicious local activities indicative of exploitation attempts. Network segmentation should be enforced to isolate critical systems and reduce lateral movement opportunities. Organizations should prioritize upgrading or migrating systems from Windows 10 Version 1809 to supported, patched versions of Windows to eliminate the vulnerability. Additionally, enforcing the principle of least privilege and regularly auditing user permissions can reduce the risk of exploitation by low-privilege users. Monitoring system logs for anomalies in Win32K subsystem behavior and educating users about the risks of local privilege escalation can further strengthen defenses. Finally, organizations should prepare incident response plans specific to local privilege escalation scenarios.