CVE-2025-21226 is an out-of-bounds read vulnerability (CWE-125) affecting Microsoft Windows 10 Version 1809 (build 10.0.17763.0). This vulnerability exists within the Windows Digital Media component and allows an attacker with low privileges (PR:L) to perform an elevation of privilege attack without requiring user interaction (UI:N). The vulnerability arises due to improper bounds checking when handling certain media-related data, enabling an attacker to read memory outside the intended buffer boundaries. This can lead to disclosure of sensitive information (confidentiality impact), and potentially allow an attacker to manipulate memory contents, resulting in integrity and availability impacts. The CVSS v3.1 base score is 6.6 (medium severity), with attack vector being physical (AV:P), meaning the attacker needs local physical access or local system access. The vulnerability does not require user interaction and affects confidentiality, integrity, and availability at a high level. No known exploits are currently reported in the wild, and no patches have been linked yet. The vulnerability was reserved in December 2024 and published in January 2025, indicating it is a recent discovery. Given the affected version is Windows 10 Version 1809, which is an older Windows 10 release, this vulnerability primarily affects systems that have not been updated to newer Windows 10 versions or Windows 11. The lack of patches and known exploits suggests that organizations should prioritize mitigation and patching once updates become available.

For European organizations, the impact of CVE-2025-21226 can be significant, especially for those still operating legacy systems running Windows 10 Version 1809. The vulnerability allows an attacker with local physical or system access to elevate privileges, potentially gaining administrative control over affected systems. This can lead to unauthorized access to sensitive data, disruption of services, and compromise of system integrity. Critical infrastructure sectors such as finance, healthcare, government, and manufacturing that rely on legacy Windows 10 deployments may face increased risk of insider threats or targeted attacks exploiting this vulnerability. The high confidentiality, integrity, and availability impacts mean that data breaches, ransomware deployment, or sabotage could result from exploitation. Additionally, the physical access requirement limits remote exploitation but raises concerns for environments with shared or poorly secured physical access, such as offices, data centers, or public terminals. Organizations with strict regulatory compliance requirements under GDPR and NIS Directive must consider the risk of data exposure and operational disruption due to this vulnerability.

1. Immediate inventory and identification of all systems running Windows 10 Version 1809 within the organization to assess exposure. 2. Prioritize upgrading or patching affected systems as soon as Microsoft releases official security updates addressing CVE-2025-21226. 3. Until patches are available, implement strict physical security controls to prevent unauthorized physical access to systems, including secure access to offices, data centers, and endpoint devices. 4. Employ endpoint detection and response (EDR) solutions to monitor for unusual privilege escalation activities or memory access anomalies. 5. Enforce the principle of least privilege to minimize the number of users with local access rights that could exploit this vulnerability. 6. Disable or restrict use of Windows Digital Media components where feasible, or apply application whitelisting to limit execution of untrusted media files. 7. Conduct user awareness training to highlight risks of physical access and insider threats. 8. Regularly review and update asset management and patch management processes to ensure timely remediation of legacy system vulnerabilities.