CVE-2025-53395 is a high-severity local privilege escalation vulnerability affecting Paramount Macrium Reflect versions up to and including 2025-06-26. The vulnerability arises from an untrusted DLL search path weakness (CWE-427) in the ReflectMonitor.exe component. Specifically, when a user with administrative privileges mounts a backup by opening a crafted .mrimgx backup file, the application loads a malicious VSSSvr.dll located in the same directory as the backup file. This DLL hijacking allows an attacker to execute arbitrary code with administrator privileges on the affected system. The attack requires local access and administrative privileges to initially mount the backup, and user interaction is necessary to open the malicious backup file. The vulnerability exploits the way ReflectMonitor.exe searches for DLLs without properly validating the path, enabling an attacker to place a malicious DLL in the same folder as the backup file and have it loaded implicitly. The CVSS v3.1 base score is 7.7, reflecting high impact on confidentiality, integrity, and availability, with low attack complexity but requiring privileges and user interaction. No known exploits are currently reported in the wild. The vulnerability was reserved on 2025-06-29 and published on 2025-08-04. No patches or fixes have been linked yet, indicating that affected organizations should prioritize mitigation and monitoring.

For European organizations, this vulnerability poses a significant risk, especially in environments where Macrium Reflect is used for backup and recovery operations. Successful exploitation leads to arbitrary code execution with administrative privileges, potentially allowing attackers to compromise system integrity, exfiltrate sensitive data, disrupt backup and recovery processes, or establish persistent footholds. This could severely impact business continuity, data confidentiality, and system availability. Organizations in sectors with strict data protection regulations such as GDPR (e.g., finance, healthcare, government) face heightened compliance risks if backups or systems are compromised. The requirement for local administrative privileges and user interaction limits remote exploitation but insider threats or attackers who have gained initial access could leverage this vulnerability to escalate privileges and move laterally within networks. The lack of a patch increases exposure time, necessitating immediate risk management. Additionally, the vulnerability could undermine trust in backup integrity, complicating incident response and recovery efforts.

1. Restrict local administrative privileges to only trusted personnel and minimize the number of users with such rights to reduce the attack surface. 2. Educate users with administrative access to avoid opening backup files (.mrimgx) from untrusted or unknown sources. 3. Implement application whitelisting or code integrity policies to prevent unauthorized DLLs from loading in the Macrium Reflect directories. 4. Monitor directories where backups are stored for unexpected or suspicious DLL files, especially VSSSvr.dll, and establish alerts for changes. 5. Use endpoint detection and response (EDR) tools to detect anomalous DLL loading or process behaviors related to ReflectMonitor.exe. 6. Isolate backup storage locations with strict access controls and consider mounting backups in controlled environments or virtual machines to limit impact. 7. Regularly review and audit backup and recovery procedures to ensure they are resilient against tampering. 8. Stay updated with vendor advisories and apply patches promptly once available. 9. Consider deploying application sandboxing or containerization for backup mounting operations to contain potential exploits.