CVE-2025-30385 is a high-severity use-after-free vulnerability (CWE-416) found in the Windows Common Log File System (CLFS) driver on Microsoft Windows 10 Version 1809 (build 10.0.17763.0). This vulnerability arises when the CLFS driver improperly handles memory, leading to a use-after-free condition. 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-level privileges. The vulnerability does not require user interaction but does require local access with some level of privileges (PR:L). The CVSS v3.1 base score is 7.8, reflecting high impact on confidentiality, integrity, and availability (all rated high), with low attack complexity and no user interaction needed. Although no public exploits have been observed in the wild yet, the vulnerability’s nature and impact make it a significant threat, especially in environments where Windows 10 Version 1809 is still in use. The lack of available patches at the time of publication increases the urgency for mitigation. The CLFS driver is a core component used for logging and system event tracking, so exploitation could compromise system stability and security, potentially allowing attackers to bypass security controls and maintain persistence.

For European organizations, this vulnerability poses a serious risk, particularly in sectors relying on legacy Windows 10 Version 1809 systems, such as government agencies, critical infrastructure, healthcare, and financial institutions. Successful exploitation could lead to unauthorized privilege escalation, enabling attackers to execute malicious code with SYSTEM privileges, access sensitive data, disrupt services, or deploy ransomware and other malware. The compromise of logging mechanisms could also hinder forensic investigations and incident response efforts. Organizations with strict regulatory requirements under GDPR and other data protection laws face additional compliance risks if this vulnerability is exploited to access or alter personal data. The local attack vector means that insider threats or attackers who gain initial footholds via other means (e.g., phishing) could leverage this vulnerability to escalate privileges and move laterally within networks, increasing the potential damage.

Given the absence of an official patch at the time of disclosure, European organizations should implement several targeted mitigations: 1) Restrict local user permissions rigorously, ensuring users operate with the least privilege necessary to limit the ability to exploit the vulnerability. 2) Employ application whitelisting and endpoint protection solutions that can detect and block attempts to exploit use-after-free conditions or unusual privilege escalation behaviors. 3) Monitor system logs and security event data for anomalies related to CLFS or unexpected privilege escalations. 4) Where possible, upgrade affected systems to a supported and patched Windows version beyond 1809 to eliminate exposure. 5) Implement network segmentation and strict access controls to reduce the risk of lateral movement if an attacker gains local access. 6) Prepare incident response plans specifically addressing privilege escalation scenarios to enable rapid detection and containment. 7) Stay alert for official patches or vendor advisories and apply them promptly once available.