CVE-2025-21320 is a medium-severity vulnerability identified in Microsoft Windows 10 Version 1809 (build 10.0.17763.0). It is categorized under CWE-532, which involves the insertion of sensitive information into log files. Specifically, this vulnerability pertains to a Windows Kernel memory information disclosure issue where sensitive kernel memory data is improperly logged. The vulnerability allows an attacker with limited privileges (requires local access and low privileges) to gain access to sensitive information through log files without requiring user interaction. The CVSS 3.1 base score is 5.5, reflecting a medium severity level. The attack vector is local (AV:L), with low attack complexity (AC:L), and requires privileges (PR:L) but no user interaction (UI:N). The impact is primarily on confidentiality (C:H), with no impact on integrity or availability. There are no known exploits in the wild at the time of publication, and no patches have been linked yet. The vulnerability could allow an attacker to extract sensitive kernel memory data from logs, potentially aiding in further privilege escalation or lateral movement within a compromised system. Since it affects Windows 10 Version 1809, which is an older but still in-use version, the threat is relevant mainly to organizations that have not upgraded to newer Windows versions or have legacy systems in operation.

For European organizations, this vulnerability poses a risk of sensitive kernel memory information leakage, which could be leveraged by attackers to gain deeper insights into system internals and potentially facilitate further attacks such as privilege escalation or targeted exploitation. Organizations in sectors with high regulatory requirements for data protection (e.g., finance, healthcare, government) could face compliance risks if sensitive information is exposed. The confidentiality breach could lead to exposure of cryptographic keys, authentication tokens, or other sensitive data residing in kernel memory. Although the vulnerability requires local access and some privileges, insider threats or attackers who have already gained limited footholds could exploit this to escalate their access. The lack of user interaction requirement means automated or stealthy exploitation is possible once local access is obtained. Given the medium severity and the absence of known exploits, the immediate risk is moderate, but the potential for escalation makes it important to address, especially in environments with legacy Windows 10 systems.

1. Upgrade affected systems from Windows 10 Version 1809 to a supported and patched version of Windows 10 or later, as newer versions are less likely to contain this vulnerability. 2. Restrict local access to systems running Windows 10 Version 1809 by enforcing strict access controls, including limiting administrative privileges and using endpoint protection solutions to detect unauthorized local access attempts. 3. Monitor and audit log files for unusual access patterns or unexpected sensitive data exposure, implementing file integrity monitoring to detect unauthorized changes or access to logs. 4. Employ application whitelisting and endpoint detection and response (EDR) tools to detect and prevent exploitation attempts that leverage kernel memory information leakage. 5. Implement network segmentation to limit lateral movement opportunities for attackers who gain local access. 6. Once a patch or update is released by Microsoft, prioritize its deployment across all affected systems. 7. Educate IT staff and users about the risks of running unsupported or outdated operating system versions and the importance of timely updates.