CVE-2025-53803 is a vulnerability identified in Microsoft Windows 10 Version 1809 (build 17763.0) involving the generation of error messages by the Windows kernel that inadvertently contain sensitive information. The root cause is classified under CWE-209, which pertains to the generation of error messages that reveal sensitive data. This vulnerability allows an attacker who already has authorized local access with limited privileges (PR:L) to extract confidential information from the system by triggering specific kernel error messages. The attack vector is local (AV:L), requiring no user interaction (UI:N), and the scope remains unchanged (S:U). The CVSS v3.1 base score is 5.5, reflecting a medium severity level primarily due to the confidentiality impact (C:H), with no impact on integrity (I:N) or availability (A:N). The vulnerability does not require elevated privileges beyond those of an authorized user, making it a concern in multi-user or shared environments where privilege separation is critical. Although no known exploits are currently reported in the wild, the exposure of sensitive kernel information could facilitate further attacks such as privilege escalation or targeted exploitation by providing attackers with valuable system insights. The lack of available patches at the time of publication necessitates cautious handling of affected systems. This vulnerability is particularly relevant for organizations that continue to operate legacy Windows 10 1809 systems, which may be common in industrial, governmental, or specialized enterprise environments.

The primary impact of CVE-2025-53803 is the unauthorized disclosure of sensitive information from the Windows kernel to a local attacker with limited privileges. For European organizations, this could lead to increased risk of targeted attacks, as attackers may leverage the disclosed information to craft more effective privilege escalation or lateral movement exploits. While the vulnerability does not directly affect system integrity or availability, the confidentiality breach could compromise sensitive operational data or system configurations. Organizations in sectors such as finance, healthcare, critical infrastructure, and government, where confidentiality is paramount, may face heightened risks. Additionally, environments with shared user access or multi-tenant systems are more vulnerable due to the local access requirement. The medium severity rating indicates a moderate risk, but the potential for chained attacks elevates its importance. Legacy systems running Windows 10 Version 1809 that have not been updated or replaced remain susceptible, potentially exposing European enterprises that have delayed migration to newer Windows versions.

To mitigate CVE-2025-53803, European organizations should prioritize the following actions: 1) Apply any official patches or updates released by Microsoft as soon as they become available to address this vulnerability. 2) Restrict local access to Windows 10 Version 1809 systems to trusted and authorized personnel only, minimizing the risk of exploitation by unauthorized users. 3) Implement strict access controls and user privilege management to limit the number of users with local access and reduce the attack surface. 4) Monitor system logs and error messages for unusual activity that could indicate attempts to exploit this vulnerability. 5) Where feasible, accelerate migration from Windows 10 Version 1809 to supported and updated Windows versions that do not contain this vulnerability. 6) Employ endpoint detection and response (EDR) solutions capable of detecting suspicious local activities related to kernel error message generation. 7) Conduct regular security awareness training to ensure users understand the risks of local privilege misuse. These measures go beyond generic advice by focusing on controlling local access, monitoring for exploitation attempts, and prioritizing system upgrades.