CVE-2025-54894 is a heap-based buffer overflow vulnerability classified under CWE-122, affecting the Local Security Authority Subsystem Service (LSASS) component of Microsoft Windows 10 Version 1809 (build 10.0.17763.0). LSASS is responsible for enforcing security policies, handling authentication, and managing user logins. The vulnerability allows a local attacker with limited privileges (PR:L) to execute a crafted input that causes a buffer overflow in the heap memory, leading to arbitrary code execution with elevated privileges. The CVSS v3.1 score of 7.8 reflects the high impact on confidentiality, integrity, and availability (all rated high), with low attack complexity and no user interaction required. Exploitation does not require network access (AV:L - local access only), but the attacker must have some level of access to the system. The vulnerability can be leveraged to escalate privileges to SYSTEM, effectively compromising the entire system. No public exploits have been reported yet, and no patches are currently linked, indicating that mitigation may rely on forthcoming updates or workarounds. The vulnerability is particularly dangerous because LSASS is a critical security process, and its compromise can lead to full system takeover, credential theft, and persistence. The affected Windows 10 Version 1809 is an older release but remains in use in some enterprise and industrial environments, increasing the risk of targeted attacks against legacy systems.

For European organizations, the impact of CVE-2025-54894 is significant. Successful exploitation allows attackers to escalate privileges to SYSTEM level, granting full control over affected machines. This can lead to unauthorized access to sensitive data, disruption of critical services, and deployment of further malware or ransomware. Organizations relying on legacy Windows 10 Version 1809 systems, especially in sectors like manufacturing, healthcare, and government, face heightened risks due to potential difficulties in patching or upgrading. The compromise of LSASS can also facilitate credential dumping attacks, enabling lateral movement within networks and broader compromise of enterprise environments. Given the high confidentiality, integrity, and availability impact, exploitation could result in severe operational disruptions and data breaches. The local attack vector limits remote exploitation but insider threats or attackers with initial footholds can leverage this vulnerability to escalate privileges and deepen their access.

Immediate mitigation should focus on applying official security patches once Microsoft releases them for Windows 10 Version 1809. Until patches are available, organizations should restrict local access to critical systems, enforce the principle of least privilege, and monitor for unusual LSASS process behavior or privilege escalation attempts. Employing endpoint detection and response (EDR) solutions with behavior-based detection can help identify exploitation attempts. Network segmentation to isolate legacy systems and disabling unnecessary local accounts can reduce attack surface. Additionally, organizations should plan to upgrade from Windows 10 Version 1809 to supported, patched versions to eliminate exposure. Regularly auditing user privileges and applying strict access controls on sensitive systems will further mitigate risk. Incident response teams should prepare to investigate potential exploitation signs, including unusual process activity or memory anomalies related to LSASS.