CVE-2025-49661 is a high-severity local privilege escalation vulnerability affecting Microsoft Windows 10 Version 1809 (build 10.0.17763.0). The vulnerability arises from an untrusted pointer dereference in the Windows Ancillary Function Driver for WinSock, a component responsible for network socket operations. Specifically, this flaw allows an authorized local attacker to manipulate pointer references that the driver trusts without proper validation, leading to memory corruption. Exploiting this vulnerability can result in the attacker gaining elevated privileges on the affected system, potentially achieving SYSTEM-level access. The vulnerability does not require user interaction but does require the attacker to have some level of local access (low privileges). The CVSS v3.1 base score is 7.8, reflecting high impact on confidentiality, integrity, and availability, with low attack complexity and no user interaction needed. Although no known exploits are currently reported in the wild, the vulnerability's characteristics make it a significant risk, especially in environments where Windows 10 Version 1809 remains in use. The absence of published patches at the time of disclosure increases the urgency for mitigation.

For European organizations, this vulnerability poses a substantial risk, particularly in sectors where legacy Windows 10 Version 1809 systems remain operational, such as industrial control systems, healthcare, and government agencies. Successful exploitation could allow attackers to escalate privileges locally, bypassing security controls and potentially deploying malware, ransomware, or conducting lateral movement within networks. This could lead to data breaches, operational disruptions, and compromise of sensitive information. Given the high confidentiality, integrity, and availability impacts, organizations could face regulatory penalties under GDPR if personal data is compromised. The vulnerability's local attack vector means that insider threats or attackers who gain initial footholds via phishing or other means could leverage this flaw to deepen their access, making incident response more complex and costly.

1. Immediate prioritization of patching: Although no patches are linked in the provided data, organizations should monitor Microsoft’s official security advisories and apply any released updates for Windows 10 Version 1809 promptly. 2. Restrict local access: Limit the number of users with local access rights on affected systems to reduce the attack surface. 3. Employ application whitelisting and endpoint protection: Use advanced endpoint detection and response (EDR) solutions to detect anomalous privilege escalation attempts. 4. Network segmentation: Isolate legacy systems running Windows 10 Version 1809 to contain potential compromises. 5. Regularly audit and monitor logs for suspicious local privilege escalation activities. 6. Consider upgrading affected systems to supported Windows versions with ongoing security updates to reduce exposure to unpatched vulnerabilities. 7. Implement strict access controls and least privilege principles to minimize the impact of potential exploitation.