CVE-2025-27742 is a medium-severity vulnerability identified in Microsoft Windows 10 Version 1809 (build 10.0.17763.0). The vulnerability is classified as an out-of-bounds read (CWE-125) within the Windows NTFS file system driver. This type of flaw occurs when the software reads data outside the boundaries of allocated memory buffers, potentially leading to unauthorized disclosure of information. Specifically, an attacker with local access to the affected system can exploit this vulnerability to read sensitive information from memory that should not be accessible, thereby compromising confidentiality. The vulnerability requires local access (attack vector: local), does not require privileges (PR:N), but does require user interaction (UI:R), such as opening a specially crafted file or mounting a malicious NTFS volume. The scope is unchanged (S:U), meaning the impact is confined to the vulnerable component without affecting other system components. The CVSS v3.1 base score is 5.5, reflecting a medium severity level with high impact on confidentiality but no impact on integrity or availability. No known exploits are currently reported in the wild, and no patches or mitigations have been linked yet. The vulnerability was reserved in early March 2025 and published in April 2025, indicating it is a recent discovery. The flaw could be leveraged by attackers to disclose sensitive data locally, which might include credentials, encryption keys, or other protected information stored in memory buffers related to NTFS operations.

For European organizations, this vulnerability poses a moderate risk primarily to systems still running Windows 10 Version 1809, which is an older release. Organizations with legacy systems or those that have not applied recent upgrades may be susceptible to local information disclosure attacks. The confidentiality breach could lead to exposure of sensitive corporate data, user credentials, or cryptographic material, potentially facilitating further attacks such as privilege escalation or lateral movement within networks. Although exploitation requires local access and user interaction, insider threats or attackers who gain initial footholds could leverage this vulnerability to escalate their information gathering capabilities. This is particularly relevant for sectors with high data sensitivity such as finance, healthcare, and government institutions across Europe. The lack of known exploits in the wild reduces immediate risk, but the presence of this vulnerability in a widely deployed OS version means that targeted attacks or insider misuse remain concerns. Additionally, organizations bound by strict data protection regulations like GDPR must consider the implications of any data leakage incidents resulting from this vulnerability.

Given the absence of an official patch at the time of this report, European organizations should prioritize upgrading affected systems from Windows 10 Version 1809 to a more recent and supported Windows version where this vulnerability is addressed. If immediate upgrade is not feasible, organizations should implement strict local access controls to limit user permissions and prevent untrusted users from executing arbitrary code or opening untrusted files. Employing application whitelisting and restricting the execution of unknown or suspicious files can reduce the risk of user interaction exploitation. Monitoring and auditing local user activities for unusual file access or mounting operations related to NTFS volumes can help detect potential exploitation attempts. Additionally, organizations should educate users about the risks of opening untrusted files or media. Network segmentation and endpoint detection and response (EDR) solutions can help contain and identify suspicious behavior stemming from exploitation attempts. Finally, organizations should stay alert for official patches or security advisories from Microsoft and apply them promptly once available.