CVE-2025-27739 is a high-severity vulnerability identified in Microsoft Windows 10 Version 1809 (build 10.0.17763.0). It is classified under CWE-822, which pertains to untrusted pointer dereference. This vulnerability exists within the Windows Kernel, the core component responsible for managing system resources and hardware interactions. The flaw allows an authorized local attacker—meaning someone with existing access to the system but limited privileges—to exploit improper handling of pointers in kernel code. By dereferencing untrusted pointers, the attacker can manipulate kernel memory, leading to elevation of privileges. This means the attacker can gain higher-level permissions than originally granted, potentially achieving SYSTEM-level access. The CVSS v3.1 score is 7.8, indicating a high severity level. The vector metrics specify that the attack requires local access (AV:L), low attack complexity (AC:L), privileges required (PR:L), no user interaction (UI:N), and impacts confidentiality, integrity, and availability (C:H/I:H/A:H). The scope remains unchanged (S:U), meaning the vulnerability affects only the vulnerable component. No known exploits are currently reported in the wild, and no patches have been linked yet. However, given the nature of kernel vulnerabilities, exploitation could allow attackers to bypass security controls, install persistent malware, or disrupt system operations. This vulnerability is particularly concerning for environments where Windows 10 Version 1809 is still in use, especially in enterprise or critical infrastructure settings where privilege escalation can lead to significant damage.

For European organizations, the impact of CVE-2025-27739 can be substantial. Many enterprises, government agencies, and critical infrastructure operators in Europe still maintain legacy systems running Windows 10 Version 1809 due to compatibility or operational constraints. An attacker exploiting this vulnerability could gain elevated privileges on affected systems, enabling lateral movement within networks, unauthorized access to sensitive data, and deployment of advanced persistent threats (APTs). The compromise of confidentiality, integrity, and availability could lead to data breaches, disruption of services, and loss of trust. Sectors such as finance, healthcare, manufacturing, and public administration are particularly at risk due to their reliance on Windows-based systems and the sensitive nature of their data. Additionally, the lack of user interaction requirement means that exploitation can be automated or triggered silently, increasing the risk of widespread impact. Although no exploits are currently known in the wild, the high severity and kernel-level nature of the vulnerability make it a prime target for attackers once exploit code becomes available.

To mitigate CVE-2025-27739, European organizations should prioritize the following actions: 1) Identify and inventory all systems running Windows 10 Version 1809 to understand exposure. 2) Apply any available security updates or patches from Microsoft immediately once released. Since no patch links are currently provided, organizations should monitor official Microsoft security advisories closely. 3) Implement strict access controls to limit local user privileges, reducing the pool of potential attackers who can exploit this vulnerability. 4) Employ endpoint detection and response (EDR) solutions capable of monitoring kernel-level activities and detecting anomalous behavior indicative of privilege escalation attempts. 5) Restrict use of legacy systems where possible by upgrading to supported Windows versions with active security updates. 6) Conduct regular security audits and penetration testing focusing on privilege escalation vectors. 7) Use application whitelisting and system hardening techniques to minimize attack surface. 8) Educate IT staff about the vulnerability and signs of exploitation to ensure rapid incident response. These targeted measures go beyond generic advice by focusing on the specific characteristics of this kernel-level untrusted pointer dereference vulnerability and the affected Windows version.