CVE-2025-49660 is a high-severity use-after-free vulnerability identified in Microsoft Windows 10 Version 1809 (build 10.0.17763.0), specifically within the Windows Event Tracing (ETW) component. The vulnerability arises due to improper handling of memory, where a pointer to a freed object is dereferenced, leading to undefined behavior. This flaw allows an authorized local attacker—who already has limited privileges—to exploit the vulnerability to escalate their privileges on the affected system. The CVSS 3.1 base score of 7.8 reflects the significant impact on confidentiality, integrity, and availability, with the attack vector being local (AV:L), requiring low attack complexity (AC:L), and low privileges (PR:L) but no user interaction (UI:N). The scope remains unchanged (S:U), meaning the vulnerability affects resources managed by the same security authority. Exploitation could lead to full system compromise, allowing the attacker to execute arbitrary code with elevated privileges, manipulate sensitive data, or disrupt system operations. Although no known exploits are currently reported in the wild, the vulnerability's nature and severity make it a critical concern for organizations still running this legacy Windows 10 version. The lack of available patches at the time of publication further increases the risk, emphasizing the need for immediate mitigation measures.

For European organizations, this vulnerability poses a substantial risk, particularly for enterprises and government agencies that continue to operate legacy Windows 10 Version 1809 systems. Successful exploitation could enable attackers to bypass existing security controls, gain administrative privileges, and potentially move laterally within corporate networks. This could lead to data breaches involving sensitive personal data protected under GDPR, intellectual property theft, disruption of critical services, and damage to organizational reputation. The vulnerability’s impact on confidentiality, integrity, and availability is high, making it a prime target for threat actors seeking to establish persistent footholds or conduct espionage. Given the local attack vector, insider threats or compromised user accounts could be leveraged to exploit this flaw. Additionally, sectors with stringent compliance requirements, such as finance, healthcare, and critical infrastructure, may face regulatory and operational consequences if exploited.

European organizations should prioritize upgrading or patching affected systems, although no official patch is currently available. Immediate mitigation steps include: 1) Identifying and inventorying all Windows 10 Version 1809 systems to assess exposure. 2) Restricting local user privileges by enforcing the principle of least privilege and limiting administrative rights to reduce the risk of exploitation. 3) Implementing application whitelisting and endpoint detection and response (EDR) solutions to monitor and block suspicious activities related to ETW or privilege escalation attempts. 4) Employing network segmentation to contain potential lateral movement from compromised hosts. 5) Encouraging users to avoid running untrusted code and maintaining strong access controls. 6) Monitoring system logs and security alerts for unusual behavior indicative of exploitation attempts. 7) Planning and executing a migration strategy to supported Windows versions with active security updates to eliminate exposure to this and similar vulnerabilities.