CVE-2025-54894 is a high-severity local privilege escalation vulnerability affecting Microsoft Windows 10 Version 1809 (build 10.0.17763.0). The vulnerability is classified as a heap-based buffer overflow (CWE-122) within the Local Security Authority Subsystem Service (LSASS). LSASS is a critical Windows component responsible for enforcing security policies, handling authentication, and managing user logins. A heap-based buffer overflow occurs when a program writes more data to a buffer located on the heap than it can hold, potentially overwriting adjacent memory and leading to arbitrary code execution or system instability. In this case, the flaw allows an attacker with limited privileges (low-level privileges) to execute code with elevated privileges, potentially SYSTEM level, without requiring user interaction. The CVSS v3.1 base score is 7.8, reflecting high impact on confidentiality, integrity, and availability, with low attack complexity and requiring only limited privileges but no user interaction. Although no known exploits are currently reported in the wild, the vulnerability's nature and affected component make it a significant risk. The absence of patch links suggests that a fix may not yet be publicly available or is pending release. Given that Windows 10 Version 1809 is an older release, organizations still running this version are at risk of exploitation if attackers gain local access. The vulnerability could be leveraged by attackers to escalate privileges after initial access, facilitating lateral movement, persistence, or deployment of malware with elevated rights.

For European organizations, this vulnerability poses a serious threat, especially in environments where Windows 10 Version 1809 remains in use, such as legacy systems or specialized industrial control systems. Successful exploitation could allow attackers to bypass security controls by elevating privileges locally, leading to full system compromise. This could result in unauthorized access to sensitive data, disruption of critical services, and potential spread of ransomware or other malware. Sectors with high reliance on Windows 10 1809, including manufacturing, healthcare, and government agencies, could face operational disruptions and data breaches. The confidentiality, integrity, and availability of systems could be severely impacted, undermining compliance with GDPR and other regulatory frameworks. Additionally, the lack of known exploits in the wild does not preclude future exploitation, and threat actors may develop exploits rapidly once details become widely known.

Organizations should prioritize upgrading affected systems to a supported and fully patched version of Windows 10 or later. If immediate upgrade is not feasible, applying any available security updates from Microsoft as soon as they are released is critical. Employing application whitelisting and restricting local user privileges can reduce the risk of exploitation. Monitoring LSASS process behavior and implementing endpoint detection and response (EDR) solutions capable of detecting anomalous privilege escalation attempts is recommended. Network segmentation to limit local access to critical systems and enforcing strong access controls can further mitigate risk. Regularly auditing systems to identify devices still running Windows 10 Version 1809 and planning their timely upgrade or decommissioning is essential. Additionally, organizations should prepare incident response plans to quickly address potential exploitation attempts.