CVE-2025-55678 is a use-after-free vulnerability classified under CWE-416 affecting the DirectX component in Microsoft Windows 11 Version 25H2 (build 10.0.26200.0). Use-after-free vulnerabilities occur when a program continues to use memory after it has been freed, potentially leading to arbitrary code execution or system corruption. In this case, the flaw allows an attacker who already has authorized local access with low privileges to exploit the vulnerability to elevate their privileges to higher levels, potentially SYSTEM or administrator. The vulnerability does not require user interaction, increasing its risk in environments where local access is possible. The CVSS v3.1 score of 7.0 reflects high severity, with attack vector local (AV:L), attack complexity high (AC:H), privileges required low (PR:L), no user interaction (UI:N), and impacts on confidentiality, integrity, and availability all rated high (C:H/I:H/A:H). No public exploits are known yet, and no patches have been released at the time of publication, but the vulnerability is publicly disclosed and should be considered a significant threat. The flaw resides in DirectX, a core multimedia API widely used in Windows for graphics and gaming, which is integral to many applications and services, increasing the attack surface. Exploitation could allow attackers to bypass security controls, install persistent malware, or disrupt critical services.

For European organizations, this vulnerability poses a serious risk to endpoint security and overall network integrity. Successful exploitation could allow attackers with limited local access—such as through compromised user accounts or insider threats—to escalate privileges and gain administrative control. This could lead to unauthorized access to sensitive data, disruption of business-critical applications, and deployment of malware or ransomware with elevated rights. Organizations in sectors such as finance, healthcare, government, and critical infrastructure are particularly vulnerable due to the potential for data breaches and operational disruption. The widespread use of Windows 11 25H2 in European enterprises and public sector environments means the attack surface is substantial. Additionally, the lack of available patches at the time of disclosure increases the window of exposure, necessitating immediate risk mitigation. The high impact on confidentiality, integrity, and availability underscores the critical need for proactive defense measures.

1. Monitor Microsoft security advisories closely and apply official patches immediately upon release to remediate the vulnerability. 2. Implement strict local privilege management policies to limit the number of users with low-level access that could be leveraged for privilege escalation. 3. Employ application whitelisting and endpoint detection and response (EDR) solutions to detect anomalous behavior indicative of exploitation attempts. 4. Conduct regular audits of user accounts and permissions to identify and remove unnecessary local access rights. 5. Use virtualization-based security features available in Windows 11, such as Credential Guard and Hypervisor-protected Code Integrity (HVCI), to reduce the impact of privilege escalation. 6. Restrict access to systems running Windows 11 25H2 to trusted personnel and networks, minimizing exposure to potential attackers. 7. Educate IT staff and users about the risks of local privilege escalation and the importance of reporting suspicious activity. 8. Prepare incident response plans that include scenarios involving privilege escalation vulnerabilities to ensure rapid containment and remediation.