CVE-2021-47791 Overview
SmartFTP Client 10.0.2909.0 contains multiple denial of service vulnerabilities that allow attackers to crash the application through specific input manipulation. Attackers can trigger crashes by entering malformed paths, using invalid IP addresses, or clearing connection history in the client's interface. This vulnerability is classified under CWE-770 (Allocation of Resources Without Limits or Throttling).
Critical Impact
Local attackers can cause application crashes through malformed input, disrupting FTP file transfer operations and potentially causing data loss during active transfers.
Affected Products
- SmartFTP Client version 10.0.2909.0
Discovery Timeline
- January 16, 2026 - CVE-2021-47791 published to NVD
- January 16, 2026 - Last updated in NVD database
Technical Details for CVE-2021-47791
Vulnerability Analysis
This vulnerability affects SmartFTP Client, a popular Windows FTP application used for secure file transfers. The application fails to properly validate user input in multiple areas of its interface, leading to denial of service conditions. The vulnerability requires local access and user interaction to exploit, as the attacker must manipulate input fields within the client application.
The denial of service can be triggered through three distinct attack vectors: entering malformed file paths in the navigation interface, providing invalid IP address formats in connection dialogs, or manipulating the connection history clearing functionality. Each of these input validation failures can cause the application to crash, terminating any active file transfers.
Root Cause
The root cause is improper input validation (CWE-770 - Allocation of Resources Without Limits or Throttling). The SmartFTP Client does not adequately sanitize or validate user-supplied input before processing, leading to unhandled exceptions that crash the application. The application fails to implement proper boundary checks and error handling for malformed data in critical input fields.
Attack Vector
The attack requires local access to the system where SmartFTP Client is installed. An attacker with the ability to interact with the application interface can exploit these vulnerabilities by:
- Entering specially crafted malformed paths in the path navigation fields
- Providing invalid or malformed IP address formats in the connection configuration
- Triggering the connection history clearing function with specific conditions
These attacks result in application crashes, effectively denying service to legitimate users and potentially causing data loss if file transfers were in progress.
Technical details and proof-of-concept information are available in the Exploit-DB #50266 advisory.
Detection Methods for CVE-2021-47791
Indicators of Compromise
- Repeated unexpected crashes of the SmartFTP.exe process
- Windows Event Log entries indicating application crashes with exception codes related to access violations or unhandled exceptions
- Crash dump files in the SmartFTP application directory or Windows temp folders
- User reports of application instability when entering paths or connection information
Detection Strategies
- Monitor for repeated application crashes using Windows Event Log monitoring for SmartFTP process terminations
- Implement endpoint detection rules to alert on unusual crash patterns for the SmartFTP Client application
- Use SentinelOne's behavioral analysis to detect abnormal application termination patterns
- Review system crash dumps for signatures matching the known vulnerability patterns
Monitoring Recommendations
- Enable Windows Error Reporting to capture crash details for forensic analysis
- Configure endpoint protection to monitor SmartFTP Client process stability
- Implement alerting for multiple application crashes within short time periods
- Review the VulnCheck Advisory for SmartFTP for updated indicators
How to Mitigate CVE-2021-47791
Immediate Actions Required
- Update SmartFTP Client to the latest available version from the SmartFTP Download Page
- Restrict local access to systems running SmartFTP Client to authorized users only
- Review user permissions to ensure only necessary personnel can access the FTP client
- Consider temporarily using alternative FTP clients for critical file transfer operations until patched
Patch Information
Users should visit the SmartFTP Official Site to download the latest version of SmartFTP Client that addresses these denial of service vulnerabilities. Ensure all instances of SmartFTP Client version 10.0.2909.0 are identified in your environment and scheduled for updates.
Workarounds
- Limit access to the SmartFTP Client application to trusted users only
- Avoid entering untrusted or unknown paths, IP addresses, or connection strings in the client
- Implement application whitelisting to prevent unauthorized users from launching SmartFTP Client
- Consider using alternative FTP clients for environments where updates cannot be immediately applied
- Monitor for application crashes and implement automatic restart mechanisms for critical file transfer operations
# Configuration example
# Verify SmartFTP Client version and check for updates
# Run from Windows command prompt to check installed version
wmic product where "name like '%%SmartFTP%%'" get name,version
# Alternative: Check SmartFTP installation directory
dir "C:\Program Files\SmartFTP Client\SmartFTP.exe" /Q
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
