CVE-2025-55236 is a vulnerability classified under CWE-367 (Time-of-check Time-of-use (TOCTOU) Race Condition) found in the Graphics Kernel component of Microsoft Windows 10 Version 1809 (build 10.0.17763.0). This race condition arises when the system checks a resource or condition and then uses it, but the state changes between these two operations, allowing an attacker to exploit the timing gap. Specifically, an authorized attacker with local access and limited privileges can trigger this race condition to execute arbitrary code with elevated privileges, potentially gaining full control over the system. The attack requires user interaction, such as running a crafted application or script, but does not require network access or prior authentication beyond local user rights. The vulnerability impacts confidentiality, integrity, and availability, as successful exploitation can lead to privilege escalation and arbitrary code execution within the kernel context. Although no public exploits are currently known, the vulnerability's nature and high CVSS score (7.3) indicate a significant risk, especially for environments where Windows 10 1809 remains in use. The vulnerability was reserved in August 2025 and published in September 2025, with no patches currently available, highlighting the need for proactive mitigation. The Graphics Kernel is a critical system component responsible for managing graphical operations, making this vulnerability particularly dangerous as it could be leveraged to bypass security controls and compromise the entire system.

For European organizations, the impact of CVE-2025-55236 is substantial, particularly for those still operating legacy Windows 10 Version 1809 systems. Exploitation allows local attackers to escalate privileges and execute arbitrary code in kernel mode, potentially leading to full system compromise. This can result in unauthorized access to sensitive data, disruption of critical services, and persistence of malicious code. Sectors such as government, finance, healthcare, and critical infrastructure are especially vulnerable due to their reliance on Windows-based systems and the sensitive nature of their data. The requirement for local access and user interaction somewhat limits remote exploitation but does not eliminate risk, as insider threats or compromised user accounts could be leveraged. The absence of patches increases exposure time, and organizations with delayed update cycles or legacy system dependencies face heightened risk. Additionally, the vulnerability could be chained with other exploits to facilitate lateral movement within networks, amplifying its impact on enterprise environments.

1. Prioritize upgrading or patching Windows 10 Version 1809 systems as soon as Microsoft releases an official fix for CVE-2025-55236. 2. Until patches are available, restrict local user privileges by enforcing the principle of least privilege, limiting the ability of users to execute untrusted code or scripts. 3. Implement application whitelisting to prevent unauthorized or suspicious executables from running. 4. Monitor local system activity for unusual behavior indicative of exploitation attempts, such as unexpected process creations or privilege escalations. 5. Use endpoint detection and response (EDR) tools to detect and block exploitation attempts targeting kernel components. 6. Educate users about the risks of running untrusted applications and the importance of reporting suspicious activity. 7. Consider isolating legacy systems from critical networks or sensitive data environments to reduce potential impact. 8. Regularly review and harden system configurations related to graphics drivers and kernel modules to minimize attack surface. 9. Maintain robust backup and recovery procedures to mitigate damage in case of successful exploitation.