CVE-2025-5667 Overview
A buffer overflow vulnerability has been identified in FreeFloat FTP Server version 1.0 affecting the REIN Command Handler component. This vulnerability allows remote attackers to send specially crafted REIN commands that overflow internal memory buffers, potentially leading to arbitrary code execution or system compromise. The exploit has been publicly disclosed, increasing the risk of active exploitation in the wild.
Critical Impact
Remote attackers can exploit this buffer overflow vulnerability in FreeFloat FTP Server's REIN Command Handler to corrupt memory and potentially execute arbitrary code without authentication.
Affected Products
- FreeFloat FTP Server 1.0
- Systems running FreeFloat FTP Server with exposed network services
Discovery Timeline
- 2025-06-05 - CVE-2025-5667 published to NVD
- 2025-06-24 - Last updated in NVD database
Technical Details for CVE-2025-5667
Vulnerability Analysis
This buffer overflow vulnerability (CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer) exists within the REIN Command Handler functionality of FreeFloat FTP Server. The FTP REIN (Reinitialize) command is designed to reset the connection state to the initial logged-out condition. However, the implementation fails to properly validate the length of input data before copying it into fixed-size memory buffers.
When an attacker sends a malformed REIN command with excessive data, the application writes beyond the allocated buffer boundaries. This memory corruption can overwrite adjacent memory regions, including return addresses on the stack or function pointers, creating an opportunity for attackers to redirect program execution flow.
Root Cause
The root cause is improper bounds checking in the REIN Command Handler. The vulnerable code path accepts user-supplied input without validating that the data length fits within the destination buffer. This is a classic buffer overflow pattern where the application uses unsafe memory copy operations without proper size validation, allowing attackers to write arbitrary data beyond allocated memory boundaries.
Attack Vector
The attack can be launched remotely over the network without requiring authentication. An attacker establishes an FTP connection to the vulnerable server and sends a malicious REIN command containing a payload designed to overflow the buffer. The attack leverages the network-accessible FTP service (typically port 21) and does not require any user interaction or special privileges.
The vulnerability mechanism exploits the REIN command processing routine. When the server receives the command, it processes the input data using memory operations that do not verify input length against buffer capacity. By crafting a payload with excessive length, attackers can overflow the buffer and corrupt adjacent memory. Technical details and exploit documentation are available through the Fitoxs Exploit Documentation reference.
Detection Methods for CVE-2025-5667
Indicators of Compromise
- Unusual FTP traffic patterns with abnormally long REIN command payloads
- FTP server process crashes or unexpected restarts
- Memory access violations or segmentation faults in FTP server logs
- Suspicious outbound connections from the FTP server process
Detection Strategies
- Monitor FTP command traffic for REIN commands exceeding normal parameter lengths
- Implement intrusion detection rules to flag oversized FTP command payloads
- Deploy network-based anomaly detection for FTP protocol deviations
- Enable crash monitoring and alerting for the FreeFloat FTP Server process
Monitoring Recommendations
- Configure logging to capture all FTP commands, particularly REIN command usage
- Implement real-time alerting for FTP server process crashes
- Monitor network traffic for patterns consistent with buffer overflow exploitation attempts
- Review system event logs for memory corruption indicators
How to Mitigate CVE-2025-5667
Immediate Actions Required
- Disable or restrict network access to FreeFloat FTP Server 1.0 immediately
- Implement network segmentation to limit exposure of the FTP service
- Consider migrating to an alternative FTP server solution with active security support
- Apply firewall rules to restrict FTP access to trusted IP addresses only
Patch Information
At the time of publication, no official patch from the vendor has been identified for this vulnerability. Organizations should evaluate alternative FTP server solutions or implement compensating controls until a security update becomes available. Monitor VulDB entry #311156 for updates on remediation status.
Workarounds
- Disable the FreeFloat FTP Server service if not operationally required
- Use network firewalls to restrict FTP access to internal trusted networks only
- Implement an application-layer firewall or web application firewall (WAF) capable of inspecting FTP protocol traffic
- Consider deploying a reverse proxy or load balancer with FTP command filtering capabilities
# Example: Restrict FTP access using iptables
# Allow FTP only from trusted internal network
iptables -A INPUT -p tcp --dport 21 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 21 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
