CVE-2025-54916 is a high-severity stack-based buffer overflow vulnerability identified in the NTFS component of Microsoft Windows 10 Version 1809 (build 10.0.17763.0). This vulnerability arises from improper handling of data within the NTFS file system driver, leading to a stack buffer overflow condition. An authorized local attacker with limited privileges (PR:L) can exploit this flaw to execute arbitrary code on the affected system without requiring user interaction (UI:N). The vulnerability impacts confidentiality, integrity, and availability, as successful exploitation allows the attacker to run code with the privileges of the vulnerable component, potentially leading to privilege escalation or system compromise. The CVSS v3.1 base score is 7.8, reflecting the high impact and relatively low attack complexity (AC:L). The scope remains unchanged (S:U), indicating that the vulnerability affects only the vulnerable component and does not extend beyond it. No known public exploits have been reported yet, and no patches or updates have been linked at the time of publication. The vulnerability is classified under CWE-121, which corresponds to stack-based buffer overflows, a common and dangerous class of memory corruption bugs that can lead to arbitrary code execution. Given that the vulnerability requires local access and authorized privileges, it is primarily a threat in environments where attackers can gain some level of access to the system, such as through compromised user accounts or insider threats. However, the ability to execute arbitrary code locally can be leveraged to elevate privileges or move laterally within a network, increasing the risk to enterprise environments.

For European organizations, this vulnerability poses a significant risk, especially in sectors where Windows 10 Version 1809 remains in use, such as legacy systems in government, healthcare, manufacturing, and critical infrastructure. Exploitation could lead to unauthorized code execution, potentially allowing attackers to escalate privileges, deploy malware, or disrupt operations. The compromise of confidentiality could expose sensitive personal data protected under GDPR, leading to regulatory penalties and reputational damage. Integrity and availability impacts could disrupt business continuity and critical services. Since the vulnerability requires local access with authorized privileges, the risk is heightened in environments with weak internal access controls or where endpoint security is insufficient. Additionally, organizations with remote desktop or VPN access to legacy Windows 10 systems may face increased exposure if attackers gain footholds through credential theft or phishing. The lack of available patches at the time of disclosure increases the urgency for mitigation to prevent exploitation.

European organizations should prioritize the following specific mitigation steps: 1) Identify and inventory all systems running Windows 10 Version 1809 (build 17763.0) to assess exposure. 2) Apply any forthcoming security updates from Microsoft immediately upon release; monitor official Microsoft security advisories closely. 3) Implement strict access controls to limit local administrative privileges and restrict the ability to execute code locally to trusted users only. 4) Employ endpoint detection and response (EDR) solutions capable of detecting anomalous behavior indicative of exploitation attempts, such as unusual NTFS driver activity or local code execution patterns. 5) Harden systems by disabling unnecessary services and restricting local login capabilities, especially on critical or sensitive machines. 6) Enforce network segmentation to limit lateral movement opportunities if a local compromise occurs. 7) Conduct user training to reduce the risk of credential compromise that could enable local access. 8) Consider upgrading affected systems to a supported and patched version of Windows 10 or later to eliminate exposure to this vulnerability. 9) Utilize application whitelisting and exploit mitigation technologies like Control Flow Guard (CFG) to reduce the likelihood of successful exploitation. These targeted measures go beyond generic advice by focusing on controlling local access, monitoring for exploitation signs, and accelerating patch deployment.