CVE-2025-50158 is a time-of-check time-of-use (TOCTOU) race condition vulnerability identified in the NTFS file system implementation of Microsoft Windows 10 Version 1809 (build 10.0.17763.0). The flaw arises when the system performs a check on a resource (such as a file or directory) and then uses that resource without ensuring the state remains unchanged between these operations. An attacker with local access can exploit this timing window to manipulate the resource state, leading to unauthorized disclosure of sensitive information. The vulnerability is classified under CWE-367, indicating a race condition between checking and using resources. The CVSS 3.1 base score is 7.0, reflecting high severity due to its impact on confidentiality, integrity, and availability. The attack vector is local (AV:L), requiring user interaction (UI:R) but no privileges (PR:N), and the attack complexity is high (AC:H), meaning exploitation requires precise timing and conditions. No public exploits have been reported yet, and no patches are currently linked, indicating the need for vigilance and proactive mitigation. This vulnerability could be leveraged to bypass security controls or leak sensitive data stored on NTFS volumes, posing risks to data confidentiality and system integrity.

For European organizations, this vulnerability poses a significant risk, especially in environments where Windows 10 Version 1809 is still in use. The ability to disclose sensitive information locally can lead to data breaches, intellectual property theft, or exposure of confidential business information. Critical infrastructure sectors such as finance, healthcare, and government agencies could face increased risk if attackers gain local access through compromised endpoints or insider threats. The integrity and availability impacts, while secondary, could also disrupt operations if exploited in chained attacks. Given the high attack complexity and requirement for local access and user interaction, the threat is more likely to be exploited in targeted attacks rather than widespread automated campaigns. However, organizations with legacy systems or insufficient endpoint security controls remain vulnerable. The lack of known exploits in the wild provides a window for mitigation before active exploitation occurs.

Organizations should prioritize upgrading or patching Windows 10 systems to versions beyond 1809 once patches become available. Until then, restrict local access to systems by enforcing strict physical and network access controls, including the use of endpoint protection solutions that monitor for suspicious local activities and race condition exploitation attempts. Implement application whitelisting and privilege management to limit the ability of untrusted users or processes to interact with NTFS resources. Conduct regular audits of user permissions and system logs to detect anomalous behavior indicative of exploitation attempts. Educate users about the risks of executing untrusted code or interacting with suspicious files, as user interaction is required for exploitation. For environments where upgrading is not immediately feasible, consider isolating vulnerable systems and employing compensating controls such as enhanced monitoring and incident response readiness. Collaborate with Microsoft and security vendors to obtain and apply security updates promptly when released.