CVE-2025-5073: Freefloat FTP Server Buffer Overflow Flaw

CVE-2025-5073 Overview

A critical buffer overflow vulnerability has been discovered in FreeFloat FTP Server 1.0. This issue affects the MKDIR Command Handler component, where improper input handling leads to a buffer overflow condition. The vulnerability can be exploited remotely over the network without authentication, potentially allowing attackers to crash the service or execute arbitrary code.

Critical Impact

Remote attackers can exploit the buffer overflow in the MKDIR Command Handler to compromise server integrity, confidentiality, and availability without requiring authentication.

Affected Products

• FreeFloat FTP Server version 1.0

Discovery Timeline

• 2025-05-22 - CVE-2025-5073 published to NVD
• 2025-06-05 - Last updated in NVD database

Technical Details for CVE-2025-5073

Vulnerability Analysis

This vulnerability is a classic buffer overflow that occurs in the MKDIR command handler of FreeFloat FTP Server. The server fails to properly validate the length of user-supplied input when processing directory creation requests. When an attacker sends an excessively long directory name parameter to the MKDIR command, the input overflows the allocated buffer, potentially overwriting adjacent memory regions.

The vulnerability is categorized under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer) and CWE-120 (Buffer Copy without Checking Size of Input), both indicating fundamental memory safety issues in how the application handles input data.

Root Cause

The root cause lies in the MKDIR Command Handler's failure to implement proper bounds checking on user-supplied directory name input. The vulnerable code copies user input into a fixed-size buffer without verifying that the input length does not exceed the buffer's capacity. This classic buffer overflow pattern allows memory corruption when attackers supply directory names exceeding the expected length.

Attack Vector

The attack can be initiated remotely over the network. An attacker connects to the FreeFloat FTP Server on its listening port and sends a specially crafted MKDIR command with an oversized directory name parameter. No authentication is required to reach the vulnerable code path.

The exploitation workflow involves:

1. Establishing a connection to the FTP server
2. Issuing an MKDIR command with an excessively long directory name
3. Triggering the buffer overflow in the MKDIR Command Handler
4. Potentially achieving code execution or causing a denial of service

The exploit has been publicly disclosed and is available through the Fitoxs Exploit Document, increasing the risk of exploitation in the wild.

Detection Methods for CVE-2025-5073

Indicators of Compromise

• Unexpected FTP server crashes or service restarts
• Abnormally long MKDIR command requests in FTP server logs
• Memory access violations or segmentation faults in server processes
• Suspicious network connections followed by service instability

Detection Strategies

• Monitor FTP traffic for MKDIR commands with unusually long directory name parameters
• Implement network intrusion detection signatures for buffer overflow patterns targeting FTP MKDIR commands
• Enable application crash monitoring and alerting for the FreeFloat FTP Server process
• Deploy endpoint detection solutions capable of identifying memory corruption exploitation attempts

Monitoring Recommendations

• Configure logging to capture full FTP command parameters for forensic analysis
• Set up alerts for FTP service crashes or unexpected restarts
• Monitor network traffic for connections exhibiting exploitation characteristics
• Implement file integrity monitoring on FTP server binaries and configuration files

How to Mitigate CVE-2025-5073

Immediate Actions Required

• Discontinue use of FreeFloat FTP Server 1.0 if possible
• Restrict network access to the FTP server using firewall rules
• Implement network segmentation to limit exposure of vulnerable systems
• Consider migrating to a maintained FTP server solution with active security support

Patch Information

No official vendor patch information is currently available for this vulnerability. FreeFloat FTP Server appears to be legacy software without active maintenance. Organizations should evaluate alternative FTP server solutions that receive regular security updates.

For additional technical information, see VulDB #309953 and VulDB CTI ID #309953.

Workarounds

• Disable or restrict the MKDIR command functionality if operationally feasible
• Place the FTP server behind a network firewall that filters malicious input
• Use a reverse proxy or application-level firewall to inspect and sanitize FTP commands
• Limit FTP server access to trusted IP addresses only
• Consider using SFTP or FTPS alternatives that may offer better security controls

# Example firewall rule to restrict FTP access (iptables)
# Allow FTP only from trusted network segment
iptables -A INPUT -p tcp --dport 21 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 21 -j DROP