CVE-2025-53147 is a high-severity use-after-free vulnerability (CWE-416) found in the Windows Ancillary Function Driver for WinSock component of Microsoft Windows 10 Version 1809 (build 10.0.17763.0). This vulnerability allows an authorized local attacker to elevate privileges on the affected system. The flaw arises when the driver improperly manages memory, leading to a use-after-free condition where memory is accessed after it has been freed. Exploiting this vulnerability requires local access with limited privileges and no user interaction, but the attacker must overcome a high attack complexity due to the need for precise timing or conditions to trigger the flaw. Successful exploitation can result in full compromise of confidentiality, integrity, and availability of the system, as the attacker can escalate privileges to SYSTEM level. The vulnerability has a CVSS 3.1 base score of 7.0, reflecting its high impact but limited attack vector (local). There are no known exploits in the wild at the time of publication, and no patches have been linked yet. The vulnerability affects a legacy Windows 10 version (1809), which is still in use in some environments but is no longer the latest supported version. The flaw is significant because the WinSock driver is a core networking component, and exploitation could allow attackers to bypass security controls and gain persistent elevated access on affected machines.

For European organizations, this vulnerability poses a significant risk especially to those still running Windows 10 Version 1809 in their enterprise environments. Privilege escalation vulnerabilities can be leveraged by attackers who have gained initial footholds through other means (e.g., phishing, malware) to fully compromise systems, move laterally, and access sensitive data. This can lead to data breaches, disruption of critical services, and potential regulatory non-compliance under GDPR due to unauthorized access to personal data. Organizations in sectors such as finance, healthcare, government, and critical infrastructure are particularly at risk because of the sensitive nature of their data and the potential impact of operational disruption. The lack of known exploits currently reduces immediate risk, but the high severity and potential for future exploit development necessitate proactive mitigation. Legacy systems running outdated Windows versions are more vulnerable, and many European enterprises still maintain such systems for compatibility reasons, increasing exposure.

1. Immediate mitigation should focus on upgrading affected systems from Windows 10 Version 1809 to a more recent, supported Windows version where this vulnerability is patched or not present. 2. If upgrading is not immediately feasible, implement strict access controls to limit local user accounts and reduce the number of users with local login privileges. 3. Employ application whitelisting and endpoint detection and response (EDR) solutions to detect and prevent suspicious privilege escalation attempts. 4. Monitor system logs and security alerts for unusual activity indicative of exploitation attempts targeting WinSock or privilege escalation. 5. Network segmentation can limit the impact of compromised machines. 6. Regularly review and apply all security updates from Microsoft as they become available, especially those addressing this vulnerability once released. 7. Conduct internal audits to identify systems still running Windows 10 Version 1809 and prioritize their remediation. 8. Educate IT staff about the risks of legacy systems and the importance of timely patching and upgrades.