CVE-2025-53134 is a vulnerability identified in the Windows Ancillary Function Driver for WinSock in Microsoft Windows 10 Version 1809 (build 17763.0). The root cause is a Time-of-check to Time-of-use (TOCTOU) race condition, classified under CWE-367, where concurrent execution involving shared resources lacks proper synchronization. This flaw allows an authorized local attacker to exploit the timing window between resource validation and usage, leading to privilege escalation. Specifically, the attacker can manipulate the state of shared resources during this window to gain higher privileges than intended. The vulnerability affects confidentiality, integrity, and availability by potentially allowing unauthorized access to sensitive data, modification of system state, or disruption of services. The CVSS v3.1 score is 7.0 (high), reflecting local attack vector, high attack complexity, low privileges required, no user interaction, and full impact on confidentiality, integrity, and availability. No public exploits are known yet, and no patches have been released at the time of reporting. The vulnerability is particularly concerning for environments where Windows 10 1809 remains in use, especially in enterprise or critical infrastructure settings where local access is possible. The lack of user interaction requirement increases the risk of automated or scripted exploitation once a proof of concept is available.

For European organizations, the impact of CVE-2025-53134 can be significant, especially in sectors relying on legacy Windows 10 1809 systems such as manufacturing, healthcare, finance, and government. Successful exploitation allows attackers with local access to elevate privileges, potentially leading to full system compromise, unauthorized data access, and disruption of critical services. This can result in data breaches, operational downtime, and regulatory non-compliance under GDPR due to unauthorized access or data integrity violations. Organizations with shared workstations or environments where multiple users have local access are particularly vulnerable. The vulnerability also poses risks to managed service providers and enterprises with remote desktop or terminal services that might allow local code execution. Although exploitation requires local access and has high complexity, insider threats or malware that gains initial foothold could leverage this flaw to escalate privileges and move laterally within networks. The absence of known exploits currently provides a window for proactive mitigation before widespread attacks occur.

1. Prioritize upgrading or patching Windows 10 systems to versions later than 1809 once Microsoft releases a security update addressing CVE-2025-53134. 2. Restrict local access to critical systems by enforcing strict access controls, limiting administrative privileges, and using endpoint protection solutions to detect suspicious local activity. 3. Employ application whitelisting and endpoint detection and response (EDR) tools to monitor for unusual process behavior indicative of exploitation attempts. 4. Harden network segmentation to limit lateral movement opportunities if local privilege escalation occurs. 5. Conduct regular audits of user accounts and permissions to minimize the number of users with local access and administrative rights. 6. Educate users about the risks of running untrusted code locally and enforce policies to prevent unauthorized software installation. 7. Implement robust logging and monitoring to detect anomalies related to WinSock driver usage or race condition exploitation patterns. 8. Consider virtual desktop infrastructure (VDI) or sandboxing solutions to isolate user sessions and reduce the impact of local exploits.