CVE-2025-55236 is a time-of-check to time-of-use (TOCTOU) race condition vulnerability identified in the Graphics Kernel component of Microsoft Windows 10 Version 1809 (build 10.0.17763.0). This vulnerability arises when the system performs a check on a resource or condition and then uses that resource without revalidating it, allowing an attacker to exploit the timing gap to manipulate the resource state between check and use. Specifically, an authorized local attacker with limited privileges can trigger this race condition to execute arbitrary code with elevated privileges. The vulnerability affects confidentiality, integrity, and availability, as successful exploitation could lead to full system compromise. The CVSS v3.1 score is 7.3 (high), reflecting the local attack vector (AV:L), low attack complexity (AC:L), required privileges (PR:L), and user interaction (UI:R). The scope remains unchanged (S:U), but the impact on confidentiality, integrity, and availability is high (C:H/I:H/A:H). No known exploits are currently reported in the wild, and no official patches have been released as of the publication date. The vulnerability is tagged under CWE-367 (TOCTOU race condition) and CWE-843 (Access of Resource Using Incompatible Type). Given the affected Windows 10 version is from 2018, many organizations may still run it due to legacy dependencies, increasing the risk profile. The lack of a patch necessitates proactive mitigation and monitoring to reduce exploitation risk.

For European organizations, this vulnerability poses a significant risk, especially for those still operating Windows 10 Version 1809 in production environments. Exploitation could allow attackers to escalate privileges locally, execute arbitrary code, and potentially gain persistent control over critical systems. This could lead to data breaches, disruption of services, and compromise of sensitive information. Industries such as finance, healthcare, manufacturing, and government entities that rely on legacy Windows 10 systems are particularly vulnerable. The requirement for local access and user interaction somewhat limits remote exploitation but does not eliminate risk from insider threats or malware that can trigger the vulnerability. The high impact on confidentiality, integrity, and availability means that successful exploitation could severely disrupt business operations and damage organizational reputation. Additionally, the absence of patches increases the window of exposure, making timely mitigation essential.

1. Restrict local access to systems running Windows 10 Version 1809 by enforcing strict physical and network access controls. 2. Implement the principle of least privilege rigorously to minimize the number of users with local access and reduce privilege levels where possible. 3. Monitor systems for unusual or suspicious activity, especially related to graphics subsystem processes and race condition exploitation attempts. 4. Employ application whitelisting and endpoint detection and response (EDR) solutions to detect and block unauthorized code execution. 5. Educate users about the risks of executing untrusted code or interacting with suspicious prompts to reduce the likelihood of user interaction exploitation. 6. Plan and prioritize upgrading or migrating systems to supported Windows versions with active security updates to eliminate exposure to this vulnerability. 7. Stay alert for official patches or mitigations from Microsoft and apply them promptly once available. 8. Use virtualization or sandboxing for legacy applications requiring Windows 10 Version 1809 to isolate potential exploitation vectors.