CVE-2025-50158 is a Time-of-Check Time-of-Use (TOCTOU) race condition vulnerability classified under CWE-367, affecting the NTFS file system implementation in Microsoft Windows 10 Version 1507 (build 10.0.10240.0). The vulnerability arises because the system performs a security check on a resource and then uses that resource without ensuring the state has not changed in the interim, creating a race condition exploitable by attackers. This flaw allows an unauthorized local attacker to disclose sensitive information by exploiting the timing gap between the check and the use of NTFS resources. The CVSS v3.1 score is 7.0 (high), reflecting the vulnerability's impact on confidentiality, integrity, and availability. The attack vector is local (AV:L), with high attack complexity (AC:H), no privileges required (PR:N), and requires user interaction (UI:R). The scope is unchanged (S:U), but the impact on confidentiality, integrity, and availability is high (C:H/I:H/A:H). The exploitability is partially functional (E:P), and the vulnerability is officially published with no known exploits in the wild. No patches have been released yet, increasing the urgency for mitigation. The vulnerability primarily affects legacy Windows 10 systems, which may still be in use in some environments due to compatibility or upgrade delays.

For European organizations, this vulnerability poses a significant risk especially to those still operating legacy Windows 10 Version 1507 systems. The ability for a local attacker to disclose sensitive information can lead to data breaches, loss of intellectual property, and compromise of critical systems. The high impact on confidentiality, integrity, and availability means that attackers could potentially manipulate or disrupt file system operations, leading to broader system instability or data corruption. Sectors such as government, finance, healthcare, and critical infrastructure that rely on legacy Windows 10 deployments are particularly vulnerable. The requirement for local access and user interaction limits remote exploitation but does not eliminate risk from insider threats or malware that can execute locally. The absence of patches increases exposure time, and organizations may face compliance and regulatory challenges if sensitive data is compromised. Additionally, the vulnerability could be leveraged as part of a multi-stage attack chain to escalate privileges or move laterally within networks.

1. Immediate mitigation should focus on upgrading affected systems from Windows 10 Version 1507 to the latest supported Windows 10 or Windows 11 versions where this vulnerability is not present. 2. Restrict local access to critical systems by enforcing strict access controls, including the use of endpoint security solutions and limiting administrative privileges. 3. Implement application whitelisting and endpoint detection and response (EDR) tools to monitor and block suspicious local activities that could exploit race conditions. 4. Educate users about the risks of interacting with untrusted applications or files that could trigger the vulnerability. 5. Conduct regular audits of legacy systems to identify and prioritize upgrade or isolation of vulnerable hosts. 6. Use file integrity monitoring to detect unauthorized changes to NTFS file system structures. 7. In environments where immediate upgrade is not feasible, consider isolating affected systems from sensitive networks and applying strict network segmentation. 8. Monitor security advisories from Microsoft for patches or workarounds and apply them promptly once available.