CVE-2020-37101 in VPN Unlimited
Summary
by MITRE • 02/03/2026
VPN Unlimited 6.1 contains an unquoted service path vulnerability that allows local attackers to inject malicious executables into the service binary path. Attackers can exploit the unquoted path in 'C:\Program Files (x86)\VPN Unlimited\' to replace the service executable and gain elevated system privileges.
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Analysis
by VulDB Data Team • 02/03/2026
The vulnerability identified as CVE-2020-37101 represents a critical security flaw in VPN Unlimited version 6.1 that stems from improper service path configuration. This issue falls under the category of unquoted service path vulnerabilities, which are classified as CWE-1287 in the CWE database and are commonly exploited by attackers seeking privilege escalation. The vulnerability exists within the Windows service installation where the executable path contains spaces but lacks proper quotation marks around the path string.
The technical implementation of this flaw occurs in the service binary path located at C:\Program Files (x86)\VPN Unlimited\ which contains a space in the directory name but does not properly quote the path when registering the service. This misconfiguration allows an attacker with local access to manipulate the service execution flow by placing a malicious executable in a directory that Windows will search before the intended service location. When the service starts, Windows will traverse the path components and execute the first matching executable it finds, potentially executing the attacker's malicious file instead of the legitimate VPN service binary.
The operational impact of this vulnerability is significant as it provides local attackers with a straightforward path to privilege escalation. Since the service runs with elevated privileges typically required for VPN operations, successful exploitation can result in full system compromise. Attackers can leverage this vulnerability to execute arbitrary code with system-level permissions, potentially leading to data exfiltration, persistent backdoors, or further network infiltration. The vulnerability is particularly dangerous because it requires minimal privileges to exploit and can be automated through simple file placement operations.
Security professionals should implement several mitigation strategies to address this vulnerability. The primary remediation involves properly quoting the service path during installation, ensuring that all directory names containing spaces are enclosed in quotation marks within the service registration. Additionally, system administrators should conduct regular audits of service paths to identify and correct similar unquoted path configurations across all installed software. The vulnerability aligns with ATT&CK technique T1068 which covers privilege escalation through service misconfiguration, and organizations should consider implementing application whitelisting policies to prevent unauthorized executable execution. Regular security patching and service configuration reviews are essential to prevent exploitation of this class of vulnerabilities in network security applications.