CVE-2025-30400 is a use-after-free vulnerability classified under CWE-416 affecting the Desktop Window Manager (DWM) component in Microsoft Windows 10 Version 1809 (build 10.0.17763.0). The flaw occurs due to improper handling of memory objects within DWM, which leads to a use-after-free condition. An authorized attacker with local access and limited privileges can exploit this vulnerability to execute arbitrary code with elevated privileges, effectively escalating their rights to SYSTEM level. The attack vector requires local access but no user interaction, making it a potent threat in environments where attackers have gained foothold but lack administrative privileges. The vulnerability impacts confidentiality, integrity, and availability by allowing attackers to bypass security controls and potentially install persistent malware or disrupt system operations. The CVSS v3.1 score of 7.8 reflects the high severity, considering the low attack complexity, low privileges required, and no user interaction needed. Although no exploits have been observed in the wild yet, the vulnerability is publicly disclosed and should be treated as a critical risk. The lack of an official patch at the time of disclosure increases the urgency for organizations to implement interim mitigations and monitor for suspicious local activity. This vulnerability primarily affects legacy Windows 10 1809 installations, which remain in use in some enterprise and industrial environments.

For European organizations, the impact of CVE-2025-30400 can be significant, especially in sectors relying on legacy Windows 10 1809 systems such as manufacturing, healthcare, and government. Successful exploitation allows attackers to elevate privileges locally, potentially leading to full system compromise, unauthorized data access, and disruption of critical services. This can result in data breaches, operational downtime, and compliance violations under regulations like GDPR. The vulnerability's ability to compromise system integrity and availability poses risks to critical infrastructure and sensitive information. Since the attack requires local access, it is particularly dangerous in environments with weak internal access controls or where attackers have already gained initial foothold through phishing or other means. The absence of known exploits in the wild currently provides a window for proactive defense, but the high severity score indicates that exploitation could have widespread consequences if leveraged by advanced threat actors targeting European organizations.

1. Apply official security patches from Microsoft immediately once available to remediate the use-after-free vulnerability in DWM. 2. Until patches are released, restrict local access to Windows 10 1809 systems by enforcing strict access controls and limiting user privileges. 3. Employ endpoint detection and response (EDR) solutions capable of detecting anomalous local privilege escalation attempts. 4. Conduct regular audits of user accounts and remove or disable unnecessary local accounts to reduce attack surface. 5. Implement application whitelisting to prevent unauthorized code execution. 6. Monitor system logs for unusual activity related to DWM or privilege escalation attempts. 7. Consider upgrading affected systems to a supported and fully patched Windows version to eliminate exposure to legacy vulnerabilities. 8. Educate IT staff and users about the risks of local privilege escalation vulnerabilities and the importance of maintaining updated systems. 9. Segment critical systems to limit lateral movement in case of compromise. 10. Use virtualization-based security features available in newer Windows versions to add layers of protection against memory corruption exploits.