CVE-2025-5221
📋 TL;DR
CVE-2025-5221 is a critical buffer overflow vulnerability in FreeFloat FTP Server 1.0.0's QUOTE command handler that allows remote attackers to execute arbitrary code or crash the service. This affects all deployments of FreeFloat FTP Server 1.0.0 with the vulnerable component enabled. Attackers can exploit this without authentication to potentially gain control of affected systems.
💻 Affected Systems
- FreeFloat FTP Server
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data theft, or ransomware deployment
Likely Case
Service disruption through denial of service or limited code execution in constrained environments
If Mitigated
Service crash with no further impact if proper network segmentation and least privilege are implemented
🎯 Exploit Status
Public exploit code is available, making this easily weaponizable by attackers with basic skills
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: None
Vendor Advisory: None
Restart Required: No
Instructions:
No official patch available. Consider migrating to a supported, actively maintained FTP server solution.
🔧 Temporary Workarounds
Disable QUOTE command
windowsDisable the vulnerable QUOTE command handler in FreeFloat FTP Server configuration
Edit FreeFloat FTP Server configuration file to remove or disable QUOTE command support
Network access restriction
windowsRestrict network access to FreeFloat FTP Server using firewall rules
netsh advfirewall firewall add rule name="Block FreeFloat FTP" dir=in action=block protocol=TCP localport=21
netsh advfirewall firewall add rule name="Block FreeFloat FTP Data" dir=in action=block protocol=TCP localport=20
🧯 If You Can't Patch
- Immediately isolate affected systems from internet and restrict internal network access
- Migrate to alternative FTP server software (vsftpd, FileZilla Server, or Windows IIS FTP)
🔍 How to Verify
Check if Vulnerable:
Check if FreeFloat FTP Server 1.0.0 is installed and running on port 21/TCPCheck Version:
Check installed programs in Windows Control Panel or examine FreeFloat FTP Server executable propertiesVerify Fix Applied:
Verify FreeFloat FTP Server is no longer running or has been replaced with alternative software📡 Detection & Monitoring
Log Indicators:
- Multiple failed QUOTE command attempts
- Unusual QUOTE command usage patterns
- Service crash logs
Network Indicators:
- Excessive QUOTE command usage in FTP traffic
- Malformed FTP commands to port 21
SIEM Query:
source="ftp.log" AND (command="QUOTE" OR "buffer overflow" OR "access violation")