CVE-2025-29837 is a security vulnerability identified in Microsoft Windows 10 Version 1809 (build 10.0.17763.0), specifically related to the Windows Installer component. The vulnerability is classified under CWE-59, which concerns improper link resolution before file access, commonly referred to as 'link following'. This flaw allows an authorized attacker with local access and low privileges (PR:L) to exploit the way Windows Installer resolves symbolic links or junction points before accessing files. By manipulating these links, the attacker can cause the system to disclose sensitive information that should otherwise be protected. The vulnerability does not require user interaction (UI:N) and affects confidentiality (C:H) without impacting integrity or availability. The attack vector is local (AV:L), meaning the attacker must have some level of access to the affected system, but the complexity of the attack is low (AC:L). The scope remains unchanged (S:U), indicating the vulnerability affects only the vulnerable component and does not propagate to other system components. No known exploits are currently in the wild, and no patches have been linked yet. The vulnerability was published on May 13, 2025, and has a CVSS v3.1 base score of 5.5, categorized as medium severity. This vulnerability could be leveraged to gain unauthorized access to sensitive files or data on affected Windows 10 systems, potentially leading to information disclosure within an organization.

For European organizations, this vulnerability poses a moderate risk primarily to confidentiality of sensitive information on endpoints running Windows 10 Version 1809. Many enterprises and public sector entities in Europe still operate legacy systems due to compatibility or budget constraints, making this vulnerability relevant. An attacker with local access—such as an insider threat, a compromised user account, or via lateral movement after initial breach—could exploit this flaw to access confidential files or configuration data, potentially exposing intellectual property, personal data protected under GDPR, or credentials. While the vulnerability does not allow remote exploitation or system compromise, the information disclosure could facilitate further attacks or data breaches. Organizations in regulated sectors like finance, healthcare, and government are particularly vulnerable due to the sensitivity of their data. The lack of available patches increases the window of exposure. Additionally, since Windows 10 Version 1809 is an older release, some organizations may have limited support or delayed patching cycles, increasing risk exposure.

European organizations should first identify and inventory all systems running Windows 10 Version 1809 to assess exposure. Until an official patch is released, implement strict local access controls and monitoring to prevent unauthorized or unnecessary local user access, including limiting administrative privileges and enforcing the principle of least privilege. Employ endpoint detection and response (EDR) solutions to monitor for suspicious activities related to file access and symbolic link manipulations. Regularly audit file system permissions and symbolic link configurations to detect anomalies. Consider upgrading affected systems to a more recent, supported Windows version where this vulnerability is not present. Additionally, enforce network segmentation to limit lateral movement opportunities that could lead to local access on vulnerable machines. Educate users about the risks of local privilege misuse and maintain strong internal security policies. Once Microsoft releases a patch, prioritize testing and deployment in all affected environments. Finally, maintain up-to-date backups and incident response plans to quickly respond if exploitation is detected.