CVE-2025-5547 Overview
A critical buffer overflow vulnerability has been discovered in FreeFloat FTP Server 1.0. This vulnerability affects the CDUP Command Handler component and allows remote attackers to exploit the buffer overflow condition through malicious input manipulation. The vulnerability can be exploited over the network without authentication, potentially leading to unauthorized access, system compromise, or denial of service conditions.
Critical Impact
Remote attackers can exploit this buffer overflow vulnerability in the CDUP Command Handler to potentially execute arbitrary code or crash the FTP server, affecting confidentiality, integrity, and availability of the system.
Affected Products
- FreeFloat FTP Server 1.0
Discovery Timeline
- 2025-06-04 - CVE-2025-5547 published to NVD
- 2025-06-24 - Last updated in NVD database
Technical Details for CVE-2025-5547
Vulnerability Analysis
The vulnerability resides in the CDUP (Change to Parent Directory) command handler of FreeFloat FTP Server 1.0. The FTP server fails to properly validate and sanitize input when processing CDUP commands, leading to a classic buffer overflow condition (CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer).
When a user sends a specially crafted CDUP command to the server, the application copies input data into a fixed-size buffer without adequate boundary checks. This allows an attacker to write data beyond the allocated buffer space, potentially overwriting adjacent memory regions including return addresses, function pointers, or other critical program data.
The exploit has been publicly disclosed, increasing the risk of active exploitation attempts against unpatched systems running FreeFloat FTP Server.
Root Cause
The root cause is improper input validation and bounds checking in the CDUP command handler. The application does not verify the length of user-supplied input before copying it into a fixed-size memory buffer, resulting in a buffer overflow condition. This is a classic memory safety issue commonly found in legacy applications written in C/C++ that lack modern memory protection mechanisms.
Attack Vector
The attack vector is network-based, allowing remote exploitation without authentication. An attacker can connect to the FTP server on the default port and send a malicious CDUP command with an oversized payload. The attack requires:
- Network connectivity to the target FTP server
- Ability to send FTP commands (CDUP)
- A crafted payload designed to overflow the buffer
The exploitation technique involves sending a CDUP command followed by excessive data that overflows the buffer. Depending on the system's memory layout and protections, this could lead to denial of service (crash) or potentially arbitrary code execution if the attacker can control the instruction pointer.
Technical details about the exploitation method are available in the Fitoxs Exploit Document.
Detection Methods for CVE-2025-5547
Indicators of Compromise
- Unusual FTP traffic patterns with abnormally long CDUP command arguments
- FTP server crashes or unexpected restarts
- Memory access violations or segmentation faults in FreeFloat FTP Server logs
- Network connections sending malformed FTP commands followed by large data payloads
Detection Strategies
- Monitor FTP traffic for CDUP commands with payloads exceeding normal parameter lengths
- Implement network intrusion detection rules to identify buffer overflow exploitation attempts targeting FTP services
- Deploy endpoint detection solutions to monitor for suspicious memory operations in the FreeFloat FTP Server process
- Enable detailed logging on FTP servers and review for anomalous command sequences
Monitoring Recommendations
- Configure network monitoring to alert on FTP command anomalies and oversized payloads
- Implement process monitoring to detect crashes or unexpected termination of the FreeFloat FTP Server
- Review system event logs for memory corruption or access violation errors
- Monitor for reconnaissance activity targeting FTP services on port 21
How to Mitigate CVE-2025-5547
Immediate Actions Required
- Discontinue use of FreeFloat FTP Server 1.0 until a patch is available
- Restrict network access to the FTP server using firewall rules to trusted IP addresses only
- Consider migrating to a more actively maintained FTP server solution
- Implement network segmentation to isolate FTP services from critical infrastructure
Patch Information
No vendor patch information is currently available in the CVE data. FreeFloat FTP Server is legacy software that may no longer receive security updates. Organizations should evaluate alternative FTP server solutions that are actively maintained and receive regular security patches. Additional vulnerability details can be found at VulDB #310997.
Workarounds
- Disable the FTP service if not required for business operations
- Implement IP-based access controls to limit connections to trusted sources only
- Deploy a Web Application Firewall (WAF) or network-based intrusion prevention system (IPS) with signatures for buffer overflow attacks
- Consider running the FTP server in a sandboxed or containerized environment to limit potential impact
- Monitor and rate-limit incoming FTP connections to reduce exploitation windows
# Example firewall configuration to restrict FTP access (iptables)
# Allow FTP only from trusted network (replace 192.168.1.0/24 with your trusted network)
iptables -A INPUT -p tcp --dport 21 -s 192.168.1.0/24 -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.
