CVE-2025-50158 is a Time-of-check Time-of-use (TOCTOU) race condition vulnerability identified in the NTFS file system component of Microsoft Windows 10 Version 1809 (build 10.0.17763.0). This vulnerability arises when the system performs a security check on a resource and then uses that resource without revalidating its state, allowing an attacker to exploit the time gap between these operations. Specifically, the race condition can be triggered locally by an unauthorized attacker who can manipulate file system operations to disclose sensitive information that should otherwise be protected. The vulnerability affects confidentiality, integrity, and availability of the system, as it can lead to unauthorized data disclosure and potentially system instability. The CVSS v3.1 base score is 7.0, indicating high severity, with attack vector local (AV:L), attack complexity high (AC:H), no privileges required (PR:N), user interaction required (UI:R), and scope unchanged (S:U). The exploitability is limited by the need for local access and user interaction, and the attack complexity is high, meaning exploitation is non-trivial. No known exploits are currently reported in the wild, and no official patches have been released as of the publication date. The vulnerability is tracked under CWE-367, which covers TOCTOU race conditions, a class of bugs that can lead to security issues when system state changes between validation and use. This vulnerability specifically targets Windows NTFS, a critical component for file system management, making it a significant risk for systems running the affected Windows 10 version.

For European organizations, the impact of CVE-2025-50158 can be substantial, particularly for those relying on Windows 10 Version 1809 in environments where local access controls are less stringent or where multiple users share systems. The vulnerability allows unauthorized local attackers to disclose sensitive information, potentially exposing confidential business data, intellectual property, or personal information protected under GDPR. The integrity and availability impacts could lead to system instability or denial of service, affecting operational continuity. Organizations in sectors such as finance, healthcare, government, and critical infrastructure are especially vulnerable due to the sensitivity of their data and the critical nature of their operations. The requirement for local access and user interaction somewhat limits remote exploitation but does not eliminate risk in environments with shared or poorly secured endpoints. Additionally, the lack of a patch increases exposure time, necessitating immediate mitigation efforts. The vulnerability could also be leveraged as part of a multi-stage attack chain, increasing its threat potential.

To mitigate CVE-2025-50158, European organizations should implement the following specific measures: 1) Restrict local access to systems running Windows 10 Version 1809 by enforcing strict physical and logical access controls, including the use of endpoint security solutions that monitor and restrict unauthorized local activities. 2) Enforce the principle of least privilege by ensuring users operate with minimal necessary permissions, reducing the risk of exploitation by non-privileged users. 3) Implement robust user authentication and session management to prevent unauthorized user interaction that could trigger the vulnerability. 4) Monitor system logs and file system activity for unusual patterns indicative of race condition exploitation attempts, using advanced endpoint detection and response (EDR) tools. 5) Where feasible, upgrade affected systems to a supported and patched version of Windows, as Windows 10 Version 1809 is an older release with limited support. 6) Educate users about the risks of local exploitation and the importance of not executing untrusted code or scripts. 7) Prepare incident response plans specifically addressing local privilege escalation and information disclosure scenarios. These targeted actions go beyond generic patching advice and focus on reducing the attack surface and detecting exploitation attempts.