CVE-2025-59206 is a use-after-free vulnerability classified 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 on the affected system. The CVSS 3.1 base score is 7.4, indicating high severity. The attack vector is local (AV:L), requiring the attacker to have local access to the system. The attack complexity is high (AC:H), meaning exploitation requires specific conditions or expertise. No privileges are required initially (PR:N), and no user interaction is needed (UI:N), which increases the risk if an attacker gains local access. The scope is unchanged (S:U), but the impact on confidentiality, integrity, and availability is high (C:H/I:H/A:H), meaning a successful exploit could fully compromise the system. Currently, there are no known exploits in the wild, and no patches have been released, though the vulnerability was reserved on 2025-09-10 and published on 2025-10-14. The vulnerability specifically affects Windows 11 Version 25H2 with ReFS deduplication enabled, a feature used primarily in enterprise environments for efficient storage management. The lack of patches and the high impact make this a critical issue for organizations relying on this platform and feature.

For European organizations, this vulnerability poses a significant risk, especially for enterprises and government agencies that utilize Windows 11 Version 25H2 with ReFS deduplication enabled. Successful exploitation could allow attackers to escalate privileges from a local, unprivileged context to full system control, potentially leading to data breaches, ransomware deployment, or disruption of critical services. The high impact on confidentiality, integrity, and availability means sensitive data could be exfiltrated or destroyed, and system operations could be severely disrupted. Organizations in sectors such as finance, healthcare, energy, and public administration, which often use advanced file systems like ReFS for data integrity and deduplication, are particularly vulnerable. The absence of known exploits currently provides a window for proactive mitigation, but the high attack complexity and local access requirement limit the immediate threat to remote attackers. Nonetheless, insider threats or attackers who have already gained initial access could leverage this vulnerability to escalate privileges and deepen their foothold.

1. Monitor Microsoft security advisories closely for the release of official patches addressing CVE-2025-59206 and apply them immediately upon availability. 2. Restrict local access to systems running Windows 11 Version 25H2 with ReFS deduplication enabled to trusted personnel only, minimizing the risk of local exploitation. 3. Implement strict access controls and endpoint protection to detect and prevent unauthorized local access or privilege escalation attempts. 4. Consider disabling ReFS deduplication temporarily if feasible and if the risk outweighs operational needs, until a patch is available. 5. Employ application whitelisting and behavior monitoring to detect anomalous activities related to privilege escalation. 6. Conduct regular security audits and vulnerability assessments focusing on local privilege escalation vectors. 7. Educate IT staff and users about the risks of local attacks and the importance of maintaining strict physical and logical access controls. 8. Use network segmentation to limit the spread of an attacker who gains local access to one system. 9. Prepare incident response plans specifically for privilege escalation scenarios to ensure rapid containment and remediation.