CVE-2024-30066 is a heap-based buffer overflow vulnerability identified in Microsoft Windows 10 Version 1809 (build 10.0.17763.0). The vulnerability resides within the Winlogon component, which is responsible for handling user logins and session management. Specifically, the flaw involves improper handling of heap memory allocations that can be exploited to overwrite memory buffers beyond their intended boundaries. This type of vulnerability is classified under CWE-122, indicating a heap-based buffer overflow. Exploiting this vulnerability could allow an attacker with limited privileges (local access with low privileges) to escalate their privileges on the affected system without requiring user interaction. The CVSS v3.1 base score is 5.5 (medium severity), with the vector indicating that the attack requires local access (AV:L), low attack complexity (AC:L), low privileges (PR:L), no user interaction (UI:N), and results in a high impact on integrity (I:H) but no impact on confidentiality or availability. The scope remains unchanged (S:U). No known exploits are currently reported in the wild, and no official patches or mitigation links have been published at the time of this analysis. The vulnerability was reserved in March 2024 and published in June 2024. Given the involvement of Winlogon, successful exploitation could allow an attacker to execute arbitrary code or commands with elevated privileges, potentially compromising system integrity and control over the affected machine.

For European organizations, this vulnerability poses a significant risk primarily to systems still running Windows 10 Version 1809, which is an older release but may remain in use in certain environments due to legacy application dependencies or delayed upgrade cycles. Exploitation could allow an attacker who has gained local access—such as through phishing, physical access, or lateral movement within a network—to escalate privileges and gain administrative control. This could lead to unauthorized changes to system configurations, installation of persistent malware, or further lateral movement within corporate networks. The integrity of critical systems could be compromised, affecting business operations, data processing, and potentially leading to regulatory compliance issues under frameworks like GDPR if system integrity impacts personal data processing. Although the vulnerability does not directly impact confidentiality or availability, the elevated privileges gained could be leveraged to conduct further attacks that do. The lack of known exploits in the wild currently reduces immediate risk, but the medium severity score and the critical role of Winlogon suggest that organizations should prioritize mitigation, especially those in sectors with high security requirements such as finance, healthcare, and government.

Given the absence of an official patch at the time of this report, European organizations should implement the following specific mitigations: 1) Restrict local access to systems running Windows 10 Version 1809 by enforcing strict physical security controls and limiting user permissions to the minimum necessary. 2) Employ application whitelisting and endpoint detection and response (EDR) solutions to monitor and block suspicious activities indicative of privilege escalation attempts. 3) Conduct thorough audits of systems to identify and prioritize upgrade paths from Windows 10 Version 1809 to supported, patched versions of Windows 10 or Windows 11, as Microsoft typically does not provide extended support for older versions. 4) Use Group Policy or local security policies to harden Winlogon and related authentication mechanisms where possible, including disabling unnecessary services or features that could be leveraged in exploitation. 5) Increase monitoring of event logs related to authentication and privilege escalation attempts to detect early signs of exploitation. 6) Educate users about the risks of local access threats and enforce strong endpoint security hygiene. Once Microsoft releases an official patch, organizations should prioritize rapid deployment across all affected systems.