Critical Privilege Escalation Flaw in IDrive Cloud Backup Client Exposes Windows Systems to Full Compromise A newly disclosed vulnerability in the IDrive Cloud Backup Client for Windows, tracked as CVE-2026-1995, allows local attackers to escalate privileges to NT AUTHORITY\SYSTEM, granting full control over affected systems. The flaw affects the widely used cloud backup solution’s Windows client, including both desktop and server editions, which manage encrypted data storage and synchronization across devices. The vulnerability stems from improper file permission handling in the `id_service.exe` background service, which runs with SYSTEM-level privileges. The service reads files from the `C:\ProgramData\IDrive` directory, using their UTF-16LE encoded contents as process execution arguments. However, weak access controls permit non-privileged users to write to this directory, enabling attackers to place or modify files that trigger arbitrary code execution under SYSTEM privileges. Exploitation requires only authenticated local access, a condition often achieved through phishing, credential theft, or insider threats. Successful attacks could allow threat actors to access sensitive backup data, disable security tools, deploy malware or ransomware, and move laterally within enterprise networks. The flaw is particularly severe due to its low complexity and high impact, posing a significant risk to organizations relying on IDrive for Windows. At the time of disclosure, no official patch has been released, though IDrive has acknowledged the issue and is developing a fix. Until a patch is available, administrators are urged to restrict write permissions on the vulnerable directory and deploy Endpoint Detection and Response (EDR) solutions to monitor suspicious activity. Additional mitigations include enforcing Group Policy controls to block unauthorized script execution. The vulnerability underscores the critical need for timely patching and access control hardening in third-party backup solutions, especially those operating with elevated privileges.