CVE-2025-55236 is a high-severity vulnerability identified in Microsoft Windows 10 Version 1809, specifically in build 10.0.17763.0. The flaw is a Time-of-Check Time-of-Use (TOCTOU) race condition located within the Graphics Kernel component. A TOCTOU race condition occurs when a system checks a condition (time-of-check) and then uses the result of that check later (time-of-use), but the state changes between these two operations, leading to inconsistent or exploitable behavior. In this case, the race condition in the Graphics Kernel allows an authorized attacker with local access to execute arbitrary code. The attacker must have some level of privileges (low privileges, as indicated by PR:L) and requires user interaction (UI:R), which suggests exploitation might involve tricking a user to perform some action. The vulnerability impacts confidentiality, integrity, and availability, as successful exploitation can lead to full code execution with elevated privileges, potentially allowing an attacker to take control of the affected system. The CVSS v3.1 base score is 7.3, reflecting a high severity level. No known exploits are reported in the wild yet, and no patches or mitigation links are currently provided, indicating this is a recently disclosed vulnerability. The vulnerability is tracked under CWE-367 (TOCTOU race condition), which is a common software weakness that can lead to privilege escalation or arbitrary code execution if exploited. The affected product is an older Windows 10 version (1809), which may still be in use in some enterprise environments but is no longer the latest supported version, potentially complicating patching and mitigation efforts.

For European organizations, this vulnerability poses a significant risk, especially for those still running Windows 10 Version 1809 in their infrastructure. Exploitation could allow attackers to execute arbitrary code locally, potentially leading to privilege escalation and full system compromise. This could result in data breaches, disruption of business operations, and lateral movement within corporate networks. The requirement for local access and user interaction somewhat limits remote exploitation but does not eliminate risk, especially in environments where insider threats or phishing attacks are plausible. Critical sectors such as finance, healthcare, and government agencies in Europe could be particularly impacted due to the sensitive nature of their data and the potential for disruption. Additionally, organizations with legacy systems or slow patch management processes are at higher risk. The lack of known exploits in the wild currently reduces immediate threat but does not preclude future exploitation, especially as threat actors often reverse-engineer disclosed vulnerabilities to develop exploits.

Given the absence of official patches at this time, European organizations should implement several targeted mitigation strategies: 1) Upgrade or migrate systems from Windows 10 Version 1809 to a more recent, supported Windows version where this vulnerability is likely addressed. 2) Restrict local access to systems running the affected version by enforcing strict access controls, limiting administrative privileges, and using endpoint protection solutions to monitor and block suspicious activities. 3) Educate users about the risks of social engineering and phishing attacks that could trigger the required user interaction for exploitation. 4) Employ application whitelisting and privilege management to reduce the impact of potential code execution. 5) Monitor system logs and security alerts for unusual behavior related to the Graphics Kernel or local privilege escalation attempts. 6) Prepare incident response plans specifically addressing local privilege escalation scenarios. 7) Stay informed on updates from Microsoft regarding patches or workarounds and apply them promptly once available.