CVE-2025-50158 is a high-severity vulnerability identified in Microsoft Windows 10 Version 1809, specifically affecting the NTFS file system implementation. The vulnerability is classified as a Time-of-Check to Time-of-Use (TOCTOU) race condition, categorized under CWE-367. This type of race condition occurs when a system checks a condition (such as file permissions or state) and then uses the resource based on that check, but the state changes between the check and the use, allowing an attacker to exploit the timing gap. In this case, the flaw resides in the NTFS driver or related components, allowing an unauthorized local attacker to disclose sensitive information. The vulnerability requires local access (AV:L), has high attack complexity (AC:H), does not require privileges (PR:N), but does require 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 confirmed (RL:O, RC:C). Although no known exploits are currently in the wild, the vulnerability poses a significant risk due to the potential for information disclosure and system compromise if exploited. The affected version is Windows 10 Version 1809 (build 10.0.17763.0), which is an older but still in-use version in some environments. The lack of available patches at the time of publication increases the urgency for mitigation and risk management.

For European organizations, this vulnerability presents a serious risk, particularly for those still operating legacy Windows 10 Version 1809 systems. The ability for an unauthorized local attacker to disclose sensitive information could lead to data breaches, exposing confidential business data, personal data protected under GDPR, or intellectual property. The high impact on integrity and availability also suggests potential for system manipulation or denial of service, which could disrupt business operations. Organizations in sectors such as finance, healthcare, government, and critical infrastructure are especially vulnerable due to the sensitivity of their data and the regulatory requirements for data protection. The requirement for local access and user interaction somewhat limits remote exploitation but does not eliminate risk, as insider threats or social engineering could facilitate exploitation. The absence of known exploits currently reduces immediate risk but does not preclude future weaponization. The vulnerability could also be leveraged as part of a multi-stage attack chain, increasing its threat profile.

Given the absence of an official patch at the time of disclosure, European organizations should implement several specific mitigations beyond generic advice: 1) Upgrade or migrate systems from Windows 10 Version 1809 to a supported and patched Windows version to eliminate exposure. 2) Restrict local user permissions rigorously, ensuring that users do not have unnecessary access to sensitive files or system components, minimizing the attack surface for local exploitation. 3) Employ application whitelisting and endpoint protection solutions capable of detecting unusual file system access patterns or race condition exploitation attempts. 4) Conduct user awareness training focused on social engineering risks that could lead to local user interaction exploitation. 5) Monitor system logs and audit trails for anomalous file system operations indicative of TOCTOU exploitation attempts. 6) Isolate critical systems physically and logically to reduce the likelihood of unauthorized local access. 7) Prepare incident response plans specifically addressing local privilege escalation and information disclosure scenarios. These measures collectively reduce the risk until an official patch is available and deployed.