CVE-2025-53788 is a Time-of-check Time-of-use (TOCTOU) race condition vulnerability identified in Microsoft Windows Subsystem for Linux (WSL2), specifically affecting version 5.0.0.0. TOCTOU vulnerabilities occur when a system checks a condition and then uses the result of that check at a later time, during which the state may have changed, allowing an attacker to exploit the timing gap. In this case, the race condition exists within WSL2, the compatibility layer that enables Linux binaries to run natively on Windows 10 and later. An authorized attacker with low privileges on the local machine can exploit this race condition to elevate their privileges, potentially gaining higher system rights than intended. The vulnerability impacts confidentiality, integrity, and availability, as the attacker could access sensitive data, modify system files, or disrupt system operations. The CVSS v3.1 score is 7.0, reflecting a high severity with the vector AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H, indicating local attack vector, high attack complexity, low privileges required, no user interaction, unchanged scope, and high impact on confidentiality, integrity, and availability. No public exploits are known at this time, and no patches have yet been released. The vulnerability was reserved on July 9, 2025, and published on August 12, 2025. This flaw is tracked under CWE-367, which covers TOCTOU race conditions. The absence of patches means organizations must rely on compensating controls until updates are available.

For European organizations, this vulnerability poses a significant risk, especially for those leveraging WSL2 for development, testing, or production environments that integrate Windows and Linux workflows. Successful exploitation could allow attackers to escalate privileges from a low-privileged local user to higher system privileges, potentially leading to unauthorized access to sensitive data, system configuration changes, or disruption of critical services. This is particularly concerning for sectors such as finance, healthcare, and critical infrastructure, where data confidentiality and system integrity are paramount. The requirement for local access limits remote exploitation but does not eliminate risk, as insider threats or compromised endpoints could be leveraged. The high impact on confidentiality, integrity, and availability means that exploitation could lead to data breaches, system downtime, or further lateral movement within networks. Organizations relying on WSL2 for automation or development pipelines may face operational disruptions if attackers exploit this vulnerability.

Until official patches are released by Microsoft, European organizations should implement the following mitigations: 1) Restrict local access to systems running WSL2 by enforcing strict user account controls and limiting administrative privileges. 2) Monitor and audit local user activities for unusual behavior indicative of privilege escalation attempts, focusing on processes interacting with WSL2. 3) Employ application whitelisting and endpoint detection and response (EDR) solutions to detect and prevent exploitation attempts. 4) Disable or limit the use of WSL2 on critical systems where it is not essential, or consider using alternative environments for Linux compatibility. 5) Prepare for rapid deployment of patches once Microsoft releases updates by maintaining an up-to-date asset inventory and patch management process. 6) Educate local users about the risks of executing untrusted code or scripts within WSL2 environments. These targeted actions go beyond generic advice by focusing on controlling local access and monitoring WSL2-specific activity.