CVE-2025-27476 is a high-severity use-after-free vulnerability (CWE-416) found in the Windows Digital Media component of Microsoft Windows 10 Version 1809 (build 10.0.17763.0). This vulnerability allows an authorized local attacker to elevate privileges on the affected system. A use-after-free flaw occurs when a program continues to use a pointer after the memory it points to has been freed, potentially leading to arbitrary code execution or system compromise. In this case, the flaw resides in the Windows Digital Media subsystem, which handles media-related operations. Exploiting this vulnerability requires local access with some level of privileges (low privileges), but no user interaction is needed. The CVSS v3.1 base score is 7.8, reflecting high impact on confidentiality, integrity, and availability, with low attack complexity and no user interaction required. Although no known exploits are currently reported in the wild, the vulnerability's characteristics make it a significant risk for privilege escalation attacks, which could allow attackers to gain SYSTEM-level access and fully compromise affected devices. The vulnerability was reserved in late February 2025 and published in early April 2025, with no patch links currently available, indicating that mitigation or fixes may still be pending or in development. Given the affected product is Windows 10 Version 1809, which is an older but still in-use version of Windows 10, systems running this version remain vulnerable until patched.

For European organizations, this vulnerability poses a critical risk to endpoint security, particularly in environments where Windows 10 Version 1809 is still deployed. Successful exploitation could allow attackers to escalate privileges from a low-privileged user account to SYSTEM level, enabling full control over the affected machine. This could lead to unauthorized access to sensitive data, installation of persistent malware, lateral movement within networks, and disruption of critical services. Industries with high reliance on legacy Windows 10 systems, such as manufacturing, healthcare, and government agencies, may face increased exposure. The lack of required user interaction and relatively low complexity of exploitation further increase the threat level. Additionally, the absence of known exploits in the wild does not preclude future exploitation, especially as threat actors often reverse-engineer published vulnerabilities to develop exploits. The impact on confidentiality, integrity, and availability is high, potentially resulting in data breaches, operational downtime, and reputational damage for European organizations.

Given the absence of an official patch at the time of this report, European organizations should implement the following specific mitigations: 1) Identify and inventory all systems running Windows 10 Version 1809 to assess exposure. 2) Where feasible, upgrade affected systems to a newer, supported Windows 10 version or Windows 11, which are not affected by this vulnerability. 3) Apply any available security updates or workarounds from Microsoft as soon as they are released. 4) Restrict local user privileges by enforcing the principle of least privilege, ensuring users do not have unnecessary administrative rights. 5) Employ application whitelisting and endpoint detection and response (EDR) solutions to monitor for suspicious activity indicative of privilege escalation attempts. 6) Harden Windows Digital Media components by disabling or limiting media-related services if not required for business operations. 7) Increase monitoring and logging of local privilege escalation attempts and anomalous behaviors on endpoints. 8) Educate IT staff and users about the risks of local privilege escalation vulnerabilities and the importance of timely patching and system upgrades.