CVE-2025-29839 is a medium-severity vulnerability classified under CWE-125 (Out-of-bounds Read) affecting Microsoft Windows 10 Version 1809 (build 10.0.17763.0). The flaw exists in the Windows File Server component, where an out-of-bounds read condition allows an unauthorized local attacker to disclose sensitive information. Specifically, this vulnerability enables reading memory outside the intended buffer boundaries, potentially exposing data that should remain protected. The vulnerability does not require any privileges or user interaction to exploit, but the attacker must have local access to the affected system. The CVSS v3.1 base score is 4.0, reflecting limited impact primarily on confidentiality, with no impact on integrity or availability. No known exploits are currently reported in the wild, and no patches have been linked yet. The vulnerability was reserved in March 2025 and published in May 2025. Given the affected version is Windows 10 Version 1809, which is an older release, many organizations may have already migrated to newer versions, but legacy systems and specialized environments may still be at risk. The out-of-bounds read could allow attackers to glean sensitive information from memory, which might aid in further attacks or data leakage. However, the scope is limited to local disclosure without remote exploitation capabilities or privilege escalation.

For European organizations, the impact of CVE-2025-29839 is primarily related to confidentiality breaches on legacy Windows 10 Version 1809 systems, especially those functioning as file servers. Organizations that maintain older Windows 10 deployments for compatibility or operational reasons could face risks of sensitive information leakage, potentially exposing internal data or credentials stored in memory. While the vulnerability does not allow remote exploitation or system compromise, insider threats or attackers with local access (e.g., via compromised accounts or physical access) could leverage this flaw to gather intelligence. This could be particularly concerning for sectors handling sensitive personal data under GDPR, such as healthcare, finance, and government agencies. The limited severity and lack of known exploits reduce the immediate threat level, but the presence of unpatched legacy systems in critical infrastructure could amplify risks. Additionally, organizations with strict compliance requirements may need to address this vulnerability to maintain regulatory adherence.

To mitigate CVE-2025-29839 effectively, European organizations should: 1) Prioritize upgrading or migrating systems from Windows 10 Version 1809 to supported, updated Windows versions where this vulnerability is resolved. 2) Implement strict access controls to limit local access to file servers, ensuring only authorized personnel can log in or execute code locally. 3) Employ endpoint detection and response (EDR) solutions to monitor for unusual local activity that could indicate attempts to exploit memory disclosure vulnerabilities. 4) Conduct regular audits of legacy systems to identify and isolate those running vulnerable versions, applying virtual patching or compensating controls if immediate upgrades are not feasible. 5) Enforce strong physical security measures to prevent unauthorized physical access to servers. 6) Monitor vendor advisories for official patches or updates addressing this vulnerability and apply them promptly upon release. 7) Educate IT staff about the risks of legacy system vulnerabilities and the importance of minimizing local access exposure. These targeted steps go beyond generic advice by focusing on legacy system management, access restriction, and proactive monitoring tailored to the nature of this local information disclosure vulnerability.