CVE-2025-53137 is a use-after-free vulnerability classified under 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 arises due to improper handling of memory, where the driver attempts to access memory after it has been freed, leading to undefined behavior. An authorized local attacker can exploit this flaw to execute arbitrary code with elevated privileges, effectively allowing privilege escalation from a lower-privileged user context to SYSTEM or equivalent. The attack vector requires local access with limited privileges and has a high attack complexity, meaning the attacker must have detailed knowledge of the system and the vulnerability to successfully exploit it. No user interaction is needed, and the scope of impact includes confidentiality, integrity, and availability of the affected system. Although no public exploits have been reported yet, the vulnerability poses a significant risk to systems still running Windows 10 Version 1809, which is an older, out-of-support version in many environments. The lack of available patches at the time of publication increases the urgency for organizations to consider mitigation strategies. The vulnerability's CVSS v3.1 base score is 7.0, reflecting its high severity due to the potential for full system compromise through local privilege escalation.

For European organizations, this vulnerability poses a substantial risk, especially for those still operating legacy Windows 10 Version 1809 systems in critical environments such as government, healthcare, finance, and industrial control systems. Successful exploitation could allow attackers to gain elevated privileges, bypassing security controls and potentially leading to data breaches, system manipulation, or disruption of services. The compromise of confidentiality, integrity, and availability could result in regulatory non-compliance, financial losses, and reputational damage. Since the vulnerability requires local access, insider threats or attackers who have already gained initial footholds could leverage this flaw to escalate privileges and move laterally within networks. The absence of known exploits in the wild currently reduces immediate risk but does not eliminate the threat, as weaponization could occur at any time. European organizations with strict data protection regulations (e.g., GDPR) must prioritize addressing this vulnerability to avoid legal and operational consequences.

1. Apply official security patches from Microsoft as soon as they become available; if no patch exists, consider upgrading affected systems to a supported Windows version that is not vulnerable. 2. Restrict local access to Windows 10 Version 1809 systems by enforcing strict access controls and limiting administrative privileges to trusted personnel only. 3. Implement endpoint detection and response (EDR) solutions to monitor for unusual local privilege escalation attempts and anomalous behavior indicative of exploitation attempts. 4. Conduct regular audits of installed Windows versions across the organization to identify and remediate legacy systems. 5. Employ application whitelisting and least privilege principles to minimize the attack surface. 6. Educate internal users about the risks of local privilege escalation vulnerabilities and the importance of reporting suspicious activity. 7. Isolate critical systems running legacy OS versions from general user networks to reduce exposure. 8. Maintain up-to-date backups and incident response plans to quickly recover from potential compromises.