Cybersecurity researchers have uncovered a critical vulnerability in Tunnelblick, a widely-used OpenVPN client for macOS, that could grant attackers complete system control. The flaw, designated CVE-2025-43711, poses a unique threat as it remains exploitable even after users delete the application, potentially affecting millions of macOS users worldwide.
Vulnerability Technical Analysis
Security researcher Egor Filatov from Positive Technologies discovered this high-severity vulnerability, which received a CVSS 3.1 score of 8.1 out of 10. The flaw affects an extensive range of Tunnelblick versions from 3.5beta06 through 6.1beta2, encompassing virtually all active installations of the popular VPN client.
Tunnelblick serves as a graphical interface for OpenVPN on macOS platforms and has gained significant adoption among privacy-conscious users. This vulnerability creates an ironic security paradox where a tool designed to protect user privacy becomes a potential attack vector for cybercriminals.
Attack Vector and Prerequisites
Successful exploitation requires two specific conditions that are commonly met in typical macOS environments. First, the attacker must have access to a user account with system modification privileges. Since administrative rights are granted by default in most home macOS installations, this requirement is satisfied for the vast majority of users.
The second condition stems from macOS application removal practices. Many users simply drag applications to the trash without realizing that system-level components may persist. In Tunnelblick’s case, a privileged system component remains active on the device, creating the exploitation pathway.
Impact Assessment
When successfully exploited, this vulnerability enables attackers to deploy malicious software that automatically gains elevated privileges during the next system boot. This level of access grants cybercriminals comprehensive system control, including:
• Installation of persistent malware and backdoors
• Unauthorized access to sensitive user data
• Modification of critical system configurations
• Establishment of covert remote access channels
Immediate Remediation Steps
The Tunnelblick development team responded promptly to the vulnerability disclosure by releasing patched versions. Users should immediately update to version 7.0, 7.1beta01, or later to eliminate the security risk completely.
Temporary Mitigation Strategies
For users unable to update immediately, security experts recommend implementing these interim protective measures:
• Retain the Tunnelblick.app file in the /Applications directory
• Operate using standard user accounts without administrative privileges
• Manually remove the /Library/LaunchDaemons/net.tunnelblick.tunnelblick.tunnelblickd.plist file if complete removal is necessary
Proper Application Removal Protocol
Users seeking to completely remove Tunnelblick should utilize the built-in uninstaller rather than simple drag-and-drop deletion. The correct procedure involves accessing the “VPN Details” window, navigating to the “Utilities” panel, and selecting the “Uninstall” option. When the built-in uninstaller is unavailable, specialized third-party uninstallation tools should be employed.
This security incident underscores the critical importance of proper application lifecycle management in macOS environments and highlights the need for continuous security monitoring, even in software designed for protection. Users should prioritize timely security updates and adopt comprehensive software management practices to maintain robust system security. The vulnerability serves as a reminder that cybersecurity requires vigilance across all aspects of system administration, from installation through complete removal of applications.
