CVE-2025-49761 is a use-after-free vulnerability categorized under CWE-416, located in the Windows Kernel of Microsoft Windows 10 Version 1809 (build 10.0.17763.0). This vulnerability arises when the kernel improperly manages memory, freeing an object while it is still in use, which can lead to memory corruption. An authorized attacker with local access can exploit this flaw to execute arbitrary code in kernel mode, effectively elevating their privileges from a standard user to SYSTEM level. The vulnerability does not require user interaction and has a low attack complexity, meaning an attacker with limited technical barriers can leverage this issue once local access is obtained. The CVSS v3.1 score of 7.8 reflects high severity, with impacts on confidentiality, integrity, and availability rated as high. No public exploits have been reported yet, but the potential for exploitation remains significant due to the critical nature of kernel-level vulnerabilities. The vulnerability was reserved in June 2025 and published in August 2025, with no official patch links available at the time of this report, indicating that affected organizations must be vigilant and consider interim mitigations. The flaw could be leveraged in targeted attacks to bypass security controls, install persistent malware, or disrupt system operations.

For European organizations, this vulnerability poses a substantial risk, particularly for those still operating legacy Windows 10 Version 1809 systems. Successful exploitation allows attackers to gain SYSTEM-level privileges, enabling 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. Sectors such as government, finance, healthcare, and critical infrastructure are especially vulnerable due to the high value of their data and services. The local attack vector means that insider threats or attackers who have gained initial footholds via other means (e.g., phishing, physical access) can escalate privileges and deepen their access. The lack of a patch at the time of disclosure increases the window of exposure. Additionally, the vulnerability could be used to bypass endpoint protection mechanisms that rely on user privilege separation. Overall, the threat undermines trust in system integrity and availability, potentially causing operational and reputational damage.

Given the absence of an official patch, European organizations should implement the following specific mitigations: 1) Restrict local access to systems running Windows 10 Version 1809 by enforcing strict physical security controls and limiting user accounts with local login rights. 2) Employ application whitelisting and endpoint detection and response (EDR) solutions to monitor and block suspicious kernel-level activities indicative of exploitation attempts. 3) Use Group Policy to disable or restrict unnecessary services and features that could be leveraged to gain local access. 4) Conduct thorough audits of user privileges and remove unnecessary administrative rights to minimize the pool of potential attackers. 5) Implement network segmentation to isolate legacy systems and reduce lateral movement opportunities. 6) Prepare for rapid deployment of patches once released by Microsoft by maintaining an up-to-date asset inventory and patch management process. 7) Educate staff on the risks of local privilege escalation and enforce strict policies on removable media and physical device access. 8) Consider upgrading affected systems to a supported Windows version with active security updates to eliminate exposure to this and similar vulnerabilities.