CVE-2025-5110: FreeFloat FTP Server Buffer Overflow Flaw

CVE-2025-5110 Overview

A critical buffer overflow vulnerability has been identified in FreeFloat FTP Server 1.0. This vulnerability exists within the VERBOSE Command Handler component of the FTP server. When exploited, an attacker can manipulate input to trigger a buffer overflow condition, potentially leading to memory corruption, denial of service, or arbitrary code execution.

The vulnerability can be exploited remotely over the network without requiring authentication, making it a significant threat to any systems running the affected FreeFloat FTP Server software.

Critical Impact

Remote attackers can exploit the buffer overflow in the VERBOSE Command Handler to corrupt memory and potentially execute arbitrary code on vulnerable FreeFloat FTP Server 1.0 installations.

Affected Products

• FreeFloat FTP Server 1.0
• Systems running freefloat_ftp_server version 1.0

Discovery Timeline

• 2025-05-23 - CVE-2025-5110 published to NVD
• 2025-06-23 - Last updated in NVD database

Technical Details for CVE-2025-5110

Vulnerability Analysis

This vulnerability is classified as CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The VERBOSE command handler in FreeFloat FTP Server 1.0 fails to properly validate the length of user-supplied input before copying it into a fixed-size buffer. This classic buffer overflow condition allows an attacker to write data beyond the allocated memory boundaries.

The exploit has been publicly disclosed, increasing the risk of exploitation in the wild. Remote attackers can leverage this vulnerability without any prior authentication, making internet-facing FTP servers particularly vulnerable.

Root Cause

The root cause of this vulnerability lies in insufficient input validation within the VERBOSE command processing routine. The FreeFloat FTP Server does not implement proper bounds checking when handling the VERBOSE command parameter, allowing oversized input to overflow the designated buffer. This is a common programming error in legacy FTP server implementations that lack modern memory safety protections.

Attack Vector

The attack can be executed remotely over the network. An attacker connects to the vulnerable FTP server and sends a specially crafted VERBOSE command containing an oversized payload. The malicious input overflows the buffer in the command handler, potentially overwriting adjacent memory regions including return addresses on the stack.

The attack requires network access to the FTP service (typically port 21) but does not require valid credentials or any form of user interaction. The attacker simply needs to establish a connection and issue the malformed command.

Detailed technical information about the vulnerability mechanism is available in the Fitoxs Exploit Document. Additional analysis can be found in the VulDB CVE Analysis #310087.

Detection Methods for CVE-2025-5110

Indicators of Compromise

• Unusual or oversized FTP VERBOSE command requests in server logs
• FTP service crashes or unexpected restarts indicating exploitation attempts
• Anomalous network traffic patterns to FTP port 21 with large payloads
• Memory access violations or segmentation faults in FTP server processes

Detection Strategies

• Monitor FTP server logs for VERBOSE commands with unusually long parameters
• Implement network intrusion detection rules to identify buffer overflow exploitation patterns in FTP traffic
• Deploy application-layer firewalls or web application firewalls configured to inspect FTP protocol traffic
• Use endpoint detection and response (EDR) solutions to identify memory corruption exploitation attempts

Monitoring Recommendations

• Enable verbose logging on FTP servers to capture all command activity
• Set up alerting for FTP service crashes or restarts which may indicate exploitation attempts
• Monitor for unusual process behavior from the FTP server process including unexpected child processes
• Review network traffic for connections to FTP servers followed by abnormal command sequences

How to Mitigate CVE-2025-5110

Immediate Actions Required

• Discontinue use of FreeFloat FTP Server 1.0 and migrate to a supported, actively maintained FTP server solution
• If the server cannot be immediately replaced, restrict network access to the FTP service to trusted IP addresses only
• Implement network segmentation to isolate systems running vulnerable FTP servers
• Deploy intrusion prevention systems (IPS) with rules to detect and block buffer overflow exploitation attempts

Patch Information

No vendor patch has been released for this vulnerability. FreeFloat FTP Server appears to be an abandoned or legacy product without active security support. Organizations are strongly advised to replace this software with a modern, actively maintained FTP server alternative.

For technical details and vulnerability tracking, refer to the VulDB entry #310087.

Workarounds

• Disable the FreeFloat FTP Server service entirely if not required for business operations
• Restrict access to the FTP server using firewall rules to allow only trusted IP addresses
• Place the FTP server behind a reverse proxy or application-layer gateway that can filter malicious commands
• Migrate to a secure, maintained alternative such as vsftpd, ProFTPD, or FileZilla Server

# Configuration example - Firewall rules to restrict FTP access
# Allow FTP only from trusted network (example using iptables)
iptables -A INPUT -p tcp --dport 21 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 21 -j DROP

# Alternatively, stop the vulnerable service entirely
net stop "FreeFloat FTP Server"
# Or on Linux
systemctl stop freefloat-ftp
systemctl disable freefloat-ftp