CVE-2025-59255 is a heap-based buffer overflow vulnerability identified in the Windows Desktop Window Manager (DWM) Core Library, specifically affecting Windows 10 Version 1809 (build 17763.0). The vulnerability is classified under CWE-122, indicating unsafe memory handling that leads to buffer overflow on the heap. This flaw allows an attacker who already has authorized local access with limited privileges to execute arbitrary code with elevated privileges, effectively enabling privilege escalation. The vulnerability does not require user interaction and has a low attack complexity, meaning exploitation is feasible without complex conditions. The CVSS v3.1 score of 7.8 reflects high severity, with impacts on confidentiality, integrity, and availability (all rated high). The scope is unchanged, meaning the vulnerability affects only the local system context. No known exploits are publicly available yet, and no patches have been released as of the publication date (October 14, 2025). The lack of patches increases the risk window for organizations still running this Windows 10 version. The vulnerability's presence in a core system library used for managing graphical windows means that exploitation could allow attackers to bypass security controls and gain system-level privileges, potentially leading to full system compromise. This is particularly concerning for legacy systems that have not been updated or migrated to newer Windows versions. The vulnerability was reserved on September 11, 2025, and published shortly after, indicating recent discovery and disclosure.

For European organizations, the impact of CVE-2025-59255 is significant, especially for those relying on Windows 10 Version 1809 in production environments. Successful exploitation allows attackers to escalate privileges locally, potentially leading to full system compromise, unauthorized access to sensitive data, and disruption of critical services. This could affect confidentiality by exposing sensitive information, integrity by allowing unauthorized modification of system files or configurations, and availability by causing system instability or denial of service. Organizations in sectors such as finance, healthcare, government, and critical infrastructure are particularly at risk due to the sensitive nature of their data and operations. The vulnerability's exploitation could facilitate lateral movement within networks, increasing the risk of widespread compromise. Since no patches are currently available, organizations face a window of exposure that requires immediate mitigation efforts. The lack of user interaction requirement and low attack complexity mean that insider threats or compromised low-privilege accounts could leverage this vulnerability effectively. This elevates the threat level for environments with multiple users or shared systems.

1. Immediate mitigation should focus on restricting local access to systems running Windows 10 Version 1809, limiting the number of authorized users to reduce the attack surface. 2. Implement strict access controls and monitoring to detect unusual local privilege escalation attempts, including enhanced logging of DWM-related processes and privilege changes. 3. Where possible, upgrade affected systems to a supported and patched version of Windows, such as Windows 10 Version 21H2 or later, which are not affected by this vulnerability. 4. Employ application whitelisting and endpoint detection and response (EDR) solutions to identify and block suspicious activities indicative of exploitation attempts. 5. In environments where upgrading is not immediately feasible, consider isolating vulnerable systems from critical network segments to limit potential lateral movement. 6. Stay alert for official patches or security advisories from Microsoft and apply them promptly once available. 7. Conduct user awareness training to minimize risks from insider threats and ensure users understand the importance of reporting unusual system behavior. 8. Regularly audit and update system configurations to ensure minimal privileges are granted and unnecessary services are disabled.