CVE-2025-55224 is a high-severity race condition vulnerability identified in the Windows Win32K graphics subsystem (GRFX) specifically affecting Microsoft Windows 10 Version 1809 (build 10.0.17763.0). The flaw arises from improper synchronization during concurrent execution involving shared resources, classified under CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization). This race condition allows an authorized local attacker—someone with limited privileges on the affected system—to execute arbitrary code with elevated privileges. The vulnerability impacts confidentiality, integrity, and availability, as successful exploitation can lead to full system compromise. The CVSS v3.1 base score is 7.8, reflecting high severity, with attack vector local (AV:L), requiring high attack complexity (AC:H), low privileges (PR:L), no user interaction (UI:N), and scope changed (S:C), indicating that the vulnerability can affect resources beyond the initially vulnerable component. The exploitability is complicated by the need for local access and high attack complexity, but no known exploits are currently reported in the wild. The vulnerability is particularly critical because the Win32K subsystem is a core component of the Windows graphical subsystem, and exploitation can enable privilege escalation from a low-privileged user to SYSTEM level, potentially allowing full control over the affected machine. No official patches or mitigations are linked yet, indicating that affected organizations must prioritize risk management and mitigation strategies until a patch is available.

For European organizations, the impact of CVE-2025-55224 is significant, especially in environments where Windows 10 Version 1809 remains in use, such as legacy systems in industrial control, government agencies, or enterprises with slow upgrade cycles. Exploitation could lead to unauthorized code execution with elevated privileges, resulting in data breaches, disruption of critical services, or deployment of ransomware and other malware. Confidentiality is at risk as attackers could access sensitive data; integrity is compromised through unauthorized code execution; availability could be affected if attackers disrupt system operations. Given the local attack vector, insider threats or attackers gaining initial foothold via phishing or other means could leverage this vulnerability to escalate privileges. The lack of user interaction requirement increases risk in automated or unattended systems. European organizations with regulatory obligations under GDPR must consider the potential for data exposure and operational disruption, which could lead to legal and financial consequences.

1. Immediate mitigation should focus on minimizing the attack surface by restricting local access to systems running Windows 10 Version 1809. Implement strict access controls and monitor for unusual local activity. 2. Employ application whitelisting and endpoint detection and response (EDR) tools to detect and block suspicious behavior indicative of exploitation attempts targeting the Win32K subsystem. 3. Disable or limit use of legacy Windows 10 Version 1809 systems where possible, prioritizing upgrades to supported, patched versions of Windows 10 or Windows 11. 4. Use Group Policy or security baselines to restrict or sandbox applications that interact heavily with the graphical subsystem, reducing the likelihood of exploitation. 5. Monitor security advisories from Microsoft closely for the release of official patches and apply them promptly. 6. Conduct regular privilege audits and enforce the principle of least privilege to reduce the impact of any local compromise. 7. Educate users and administrators about the risks of local privilege escalation vulnerabilities and the importance of maintaining updated systems.