CVE-2025-55226 is a vulnerability classified under CWE-362, which involves a race condition due to improper synchronization in the Graphics Kernel component of Microsoft Windows 10 Version 1809 (build 10.0.17763.0). This flaw allows an authorized attacker with local access and low privileges to exploit concurrent execution of shared resources, leading to potential arbitrary code execution with elevated privileges. The race condition occurs when multiple threads or processes access shared resources without proper locking mechanisms, causing inconsistent or unexpected behavior. Successful exploitation requires user interaction and has a high attack complexity, meaning it is not trivial to execute but feasible under certain conditions. The vulnerability impacts confidentiality, integrity, and availability of the system by enabling code execution that could compromise system security. Although no public exploits are known, the vulnerability is significant due to the critical nature of the Graphics Kernel and the potential for privilege escalation. The CVSS v3.1 score of 6.7 reflects medium severity, with attack vector local, attack complexity high, privileges required low, user interaction required, and complete impact on confidentiality, integrity, and availability. The vulnerability was published on September 9, 2025, and no patches were listed at the time of reporting, indicating that mitigation may require upgrading or applying future updates.

For European organizations, this vulnerability poses a risk primarily to systems still running Windows 10 Version 1809, which is an older release and may be prevalent in legacy environments. The ability for a low-privileged local user to escalate privileges and execute arbitrary code could lead to full system compromise, data breaches, or disruption of critical services. Sectors such as government, healthcare, finance, and critical infrastructure that rely on legacy Windows 10 installations are at heightened risk. The impact extends to confidentiality, as sensitive data could be accessed or exfiltrated; integrity, through unauthorized code execution and system modification; and availability, if attackers disrupt services or cause system crashes. Although exploitation requires local access and user interaction, insider threats or social engineering could facilitate attacks. The absence of known exploits in the wild reduces immediate risk but does not eliminate the threat, especially as attackers may develop exploits over time. The medium severity rating suggests that while urgent patching is recommended, the threat is not currently critical but should not be ignored.

European organizations should first identify and inventory all systems running Windows 10 Version 1809 to assess exposure. Since no patches are currently listed, organizations should plan to upgrade affected systems to a supported and updated Windows version that includes fixes for this vulnerability. Until upgrades are complete, restrict local user privileges to the minimum necessary, enforce strict access controls, and monitor for unusual local activity that could indicate exploitation attempts. Implement application whitelisting and endpoint detection and response (EDR) solutions to detect and block suspicious behavior related to privilege escalation. Educate users about the risks of social engineering and the need to avoid executing untrusted code or files. Network segmentation can limit the spread of an attack originating from a compromised local account. Regularly review and update security policies to ensure legacy systems are phased out or adequately protected. Engage with Microsoft support channels for any interim mitigation guidance or patches as they become available.