CVE-2025-59210 is a use-after-free vulnerability categorized under CWE-416, found in the Windows Resilient File System (ReFS) Deduplication Service on Windows 11 Version 25H2 (build 10.0.26200.0). The vulnerability arises when the deduplication service improperly manages memory, leading to a use-after-free condition that can be exploited to elevate privileges. An attacker with local access but no prior privileges can leverage this flaw to execute arbitrary code with elevated privileges, potentially gaining full control over the affected system. The CVSS v3.1 base score is 7.4, indicating high severity, with the vector specifying local attack vector (AV:L), high attack complexity (AC:H), no privileges required (PR:N), no user interaction (UI:N), unchanged scope (S:U), and high impact on confidentiality, integrity, and availability (C:H/I:H/A:H). No public exploits or patches are currently available, but the vulnerability is officially published and reserved as of September 2025. The ReFS deduplication feature is typically used in environments requiring efficient storage management, such as enterprise file servers and data centers. Exploitation could allow attackers to bypass security controls, access sensitive data, or disrupt system operations. Due to the local access requirement and high complexity, exploitation is more challenging but remains a significant risk in environments where attackers can gain initial foothold or insider threats exist.

For European organizations, the impact of CVE-2025-59210 could be substantial, particularly in sectors relying on Windows 11 25H2 with ReFS deduplication enabled, such as financial services, healthcare, government, and critical infrastructure. Successful exploitation could lead to unauthorized privilege escalation, enabling attackers to access sensitive data, manipulate or destroy files, and disrupt business operations. This could result in data breaches, regulatory non-compliance (e.g., GDPR violations), operational downtime, and reputational damage. The requirement for local access limits remote exploitation but does not eliminate risk, especially in environments with shared workstations, remote desktop services, or insider threats. The high impact on confidentiality, integrity, and availability means that compromised systems could be fully controlled by attackers, potentially facilitating lateral movement and further attacks within networks. European organizations with stringent data protection requirements must prioritize addressing this vulnerability to prevent severe consequences.

1. Restrict local access to systems running Windows 11 Version 25H2 with ReFS deduplication enabled, enforcing strict access controls and least privilege principles. 2. Monitor and audit local user activities, especially those involving file system operations and deduplication services, to detect anomalous behavior indicative of exploitation attempts. 3. Disable ReFS deduplication if not essential, or isolate systems using this feature from general user access to reduce attack surface. 4. Implement application whitelisting and endpoint detection and response (EDR) solutions to identify and block suspicious privilege escalation attempts. 5. Prepare for rapid deployment of official patches from Microsoft once released, including testing in controlled environments before production rollout. 6. Educate IT and security teams about this vulnerability and ensure incident response plans include scenarios involving local privilege escalation via file system services. 7. Regularly update and harden system configurations to minimize potential attack vectors that could lead to local access, such as disabling unnecessary services and enforcing strong authentication mechanisms.