CVE-2024-21443 is a high-severity vulnerability classified as a Use After Free (CWE-416) in the Windows Kernel component of Microsoft Windows 10 Version 1809 (build 10.0.17763.0). This vulnerability allows an attacker with limited privileges (requires local access and low privileges) to elevate their privileges to SYSTEM level by exploiting improper handling of kernel memory, leading to use-after-free conditions. The vulnerability requires user interaction and local access, but the attack complexity is low, and no authentication beyond local access is needed. Successful exploitation can result in full confidentiality, integrity, and availability compromise of the affected system, allowing an attacker to execute arbitrary code in kernel mode, install programs, view, change, or delete data, or create new accounts with full user rights. Although no known exploits are currently observed in the wild, the vulnerability's characteristics make it a significant risk, especially for systems still running the older Windows 10 Version 1809, which is out of mainstream support and may lack recent security updates. The vulnerability was publicly disclosed on March 12, 2024, and no official patches have been linked yet, increasing the urgency for mitigation. The CVSS v3.1 base score is 7.3, reflecting high severity with local attack vector, low attack complexity, required privileges, and user interaction.

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. Exploitation could lead to unauthorized privilege escalation, enabling attackers to gain full control over affected machines. This can facilitate lateral movement within networks, data exfiltration, deployment of ransomware, or sabotage of critical infrastructure. The confidentiality, integrity, and availability of sensitive data and systems could be severely compromised. Given that many European organizations have diverse IT environments with legacy systems still in use, the risk of exploitation is non-trivial. Additionally, sectors such as finance, healthcare, and public administration, which handle sensitive personal and operational data, could face regulatory and reputational damage if exploited. The lack of known exploits in the wild currently provides a window for proactive mitigation, but the presence of a publicly known vulnerability increases the likelihood of future exploitation attempts.

European organizations should prioritize identifying and inventorying all systems running Windows 10 Version 1809. Immediate mitigation steps include: (1) applying any available security updates or patches from Microsoft as soon as they are released; (2) if patches are not yet available, consider upgrading affected systems to a supported and fully patched Windows version to eliminate exposure; (3) restrict local user privileges to the minimum necessary to reduce the attack surface; (4) implement application whitelisting and endpoint detection and response (EDR) solutions to detect suspicious kernel-level activity; (5) enforce strict user interaction policies and educate users about the risks of executing untrusted code or files; (6) monitor system logs and security alerts for signs of exploitation attempts; (7) segment networks to limit lateral movement if a system is compromised; and (8) maintain regular backups and incident response plans tailored to privilege escalation scenarios. These targeted actions go beyond generic advice by focusing on legacy system management, privilege restriction, and proactive detection tailored to kernel-level vulnerabilities.