CVE-2025-64661 is a race condition vulnerability categorized under CWE-362 affecting the Windows Shell component in Microsoft Windows 10 Version 1809 (build 10.0.17763.0). The flaw arises from improper synchronization when multiple threads or processes concurrently access shared resources, leading to a race condition. This condition can be exploited by an attacker with low-level local privileges to elevate their privileges to higher levels, potentially SYSTEM or administrator. The vulnerability does not require user interaction but does require local access, which means an attacker must already have some foothold on the system. The race condition can cause inconsistent or unexpected behavior in the Windows Shell, allowing the attacker to execute code or commands with elevated privileges. The CVSS v3.1 base score is 7.8, indicating high severity, with the vector showing local attack vector (AV:L), high attack complexity (AC:H), low privileges required (PR:L), no user interaction (UI:N), and scope changed (S:C). The impact on confidentiality, integrity, and availability is high (C:H/I:H/A:H), meaning the attacker can fully compromise the system. No public exploits are currently known, but the vulnerability is published and should be addressed promptly. The lack of available patches at the time of publication suggests organizations must implement interim mitigations and monitor for exploitation attempts. This vulnerability is particularly relevant for environments still running Windows 10 Version 1809, which is an older but still in-use version in some enterprises.

For European organizations, the impact of CVE-2025-64661 can be significant. Successful exploitation allows an attacker with limited local access to escalate privileges to administrative levels, potentially leading to full system compromise. This can result in unauthorized data access, manipulation, or destruction, disruption of critical services, and lateral movement within networks. Sectors such as finance, healthcare, government, and critical infrastructure are at heightened risk due to the sensitivity and criticality of their data and systems. Organizations running legacy Windows 10 Version 1809 systems, often found in industrial control systems or long-life enterprise environments, are particularly vulnerable. The high impact on confidentiality, integrity, and availability means that exploitation could lead to data breaches, operational downtime, and regulatory non-compliance under GDPR and other European data protection laws. The absence of known exploits in the wild currently reduces immediate risk but does not eliminate the threat, especially as attackers may develop exploits over time.

1. Apply official patches from Microsoft as soon as they become available to address this vulnerability directly. 2. Until patches are available, restrict local access to systems running Windows 10 Version 1809 by enforcing strict access controls and limiting user privileges. 3. Employ application whitelisting and endpoint detection and response (EDR) solutions to monitor and block suspicious local privilege escalation attempts. 4. Conduct thorough audits of systems to identify any unauthorized local accounts or processes that could be leveraged for exploitation. 5. Consider upgrading affected systems to a supported and fully patched Windows version to reduce exposure to legacy vulnerabilities. 6. Implement network segmentation to limit lateral movement if a local compromise occurs. 7. Educate IT staff and users about the risks of local privilege escalation and enforce policies to prevent installation of unauthorized software or scripts. 8. Monitor security advisories and threat intelligence feeds for any emerging exploit code or attack campaigns targeting this vulnerability.