CVE-2024-30091 is a heap-based buffer overflow vulnerability classified under CWE-122, affecting the Win32k subsystem in Microsoft Windows 10 Version 1809 (build 10.0.17763.0). The vulnerability allows an attacker with low privileges and local access to execute a carefully crafted attack that triggers the buffer overflow, leading to an elevation of privilege. This means an attacker can gain higher-level system privileges than originally granted, potentially allowing them to execute arbitrary code with SYSTEM-level permissions. The flaw resides in the way Win32k handles certain objects or data in memory, where insufficient bounds checking leads to overwriting adjacent memory on the heap. The vulnerability does not require user interaction, increasing its risk profile, but it does require local access and low-level privileges, limiting remote exploitation. The CVSS 3.1 score of 7.8 reflects high impact on confidentiality, integrity, and availability, with partial complexity in exploitation and no user interaction needed. No public exploits have been reported yet, but the vulnerability is publicly known since June 11, 2024. The lack of patch links suggests that organizations must monitor Microsoft advisories closely for updates or consider upgrading to newer Windows versions that do not include this vulnerability.

For European organizations, the impact of CVE-2024-30091 is significant, especially for those still operating legacy Windows 10 Version 1809 systems. Successful exploitation can lead to full system compromise, allowing attackers to bypass security controls, access sensitive data, install persistent malware, or disrupt operations. Critical sectors such as government, finance, healthcare, and industrial control systems that rely on legacy Windows environments are particularly vulnerable. The requirement for local access limits the attack vector primarily to insiders, compromised accounts, or attackers who have already gained foothold via other means. However, once exploited, the attacker gains elevated privileges, which can facilitate lateral movement and further attacks within the network. The absence of known exploits in the wild currently reduces immediate risk but does not eliminate the threat, as attackers may develop exploits rapidly following public disclosure.

1. Immediately assess and inventory all systems running Windows 10 Version 1809 (build 10.0.17763.0) within the organization. 2. Apply any available security patches from Microsoft as soon as they are released; monitor Microsoft Security Update Guide and related advisories closely. 3. Where patching is not feasible, plan and execute an upgrade to a supported Windows version that is not affected by this vulnerability. 4. Restrict local access to critical systems by enforcing strict access controls and using endpoint protection solutions to detect suspicious privilege escalation attempts. 5. Implement application whitelisting and least privilege principles to minimize the impact of potential exploitation. 6. Monitor system logs and security telemetry for unusual behavior indicative of privilege escalation attempts, such as unexpected Win32k calls or memory corruption alerts. 7. Conduct user awareness training to reduce the risk of initial foothold by attackers, as local access is required. 8. Employ network segmentation to limit lateral movement if an attacker gains elevated privileges on one system.