CVE-2016-15003 in FileZilla
Summary
by MITRE • 07/18/2022
A vulnerability has been found in FileZilla Client 3.17.0.0 and classified as problematic. This vulnerability affects unknown code of the file C:\Program Files\FileZilla FTP Client\uninstall.exe of the component Installer. The manipulation leads to unquoted search path. The attack can be initiated remotely. The exploit has been disclosed to the public and may be used.
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Analysis
by VulDB Data Team • 07/26/2026
This vulnerability in FileZilla Client 3.17.0.0 represents a critical security flaw classified as an unquoted search path issue within the installer component. The vulnerability exists in the uninstall.exe file located at C:\Program Files\FileZilla FTP Client\uninstall.exe, where the installation path contains spaces but lacks proper quotation marks around the executable path. This creates a dangerous condition where Windows will attempt to execute files from any directory in the PATH environment variable that matches the unquoted path components, potentially allowing attackers to place malicious executables in strategic locations.
The technical flaw stems from improper handling of file paths during installation processes, specifically when the installer does not properly quote paths containing spaces. This issue falls under CWE-178, which addresses improper handling of quoted strings in command line arguments and search paths. The vulnerability creates a privilege escalation vector since the uninstall.exe process typically runs with elevated privileges, allowing an attacker to execute arbitrary code with system-level permissions when the uninstallation process is initiated.
The operational impact of this vulnerability extends beyond simple code execution, as it enables attackers to perform persistent malicious activities through the installer component. This represents a significant concern for enterprise environments where FileZilla clients are widely deployed, as the attack can be initiated remotely without requiring local access to the system. The public disclosure of the exploit means that threat actors have readily available tools to leverage this weakness across multiple systems.
Attackers can exploit this vulnerability by placing malicious executables in directories that appear earlier in the PATH variable, specifically matching components of the unquoted path. This aligns with ATT&CK technique T1036.005, which covers the use of legitimate credentials and system tools to bypass security controls. The vulnerability is particularly dangerous because it affects the uninstaller process, which may be triggered during normal system maintenance or user-initiated removal processes, providing multiple attack vectors for exploitation.
Organizations should immediately update to FileZilla versions that address this unquoted search path vulnerability, as the public availability of exploit code increases the likelihood of successful attacks. The recommended mitigation strategy includes implementing application whitelisting policies and ensuring proper PATH variable management to prevent malicious executables from being loaded. Additionally, system administrators should conduct thorough audits of installed software components to identify and remediate similar vulnerabilities in other applications that may be susceptible to unquoted search path attacks.
The vulnerability demonstrates the critical importance of secure coding practices during installer development, particularly regarding proper handling of file paths and environment variables. Organizations should establish comprehensive software supply chain security measures that include regular vulnerability assessments of third-party applications and their installation components. This incident underscores the need for robust input validation and path handling mechanisms in all system components, as unquoted search path vulnerabilities continue to represent a significant attack surface in enterprise environments.
Security professionals should monitor for indicators of compromise related to this specific vulnerability through endpoint detection and response systems, focusing on unusual process execution patterns involving the uninstall.exe component. The remediation process requires careful attention to ensure that any updates or patches do not inadvertently introduce new vulnerabilities while addressing the existing unquoted search path issue. Regular security awareness training should emphasize the risks associated with installer components and the importance of maintaining secure system configurations to prevent exploitation of such fundamental security flaws.