CVE-2025-4239 is a buffer overflow vulnerability identified in PCMan FTP Server version 2.0.7, specifically within the TYPE Command Handler component. The vulnerability arises from improper handling of input data related to the FTP TYPE command, which allows an attacker to send specially crafted requests that overflow a buffer in the server's memory. This overflow can lead to arbitrary code execution or cause the server to crash, resulting in denial of service. The vulnerability is remotely exploitable without requiring authentication or user interaction, increasing its risk profile. Although the exact internal code details are unspecified, the vulnerability's classification as a buffer overflow indicates that the server fails to properly validate or limit the size of input data before copying it into a fixed-size buffer. The CVSS 4.0 base score is 6.9, reflecting medium severity, with attack vector network (remote), low complexity, no privileges or user interaction needed, and limited impact on confidentiality, integrity, and availability. No public exploits are currently known to be actively used in the wild, but the exploit code has been disclosed publicly, raising the risk of future exploitation. No patches or mitigation links have been provided yet, indicating that organizations using this FTP server version remain vulnerable until an official fix is released. PCMan FTP Server is a lightweight FTP server software commonly used in small to medium environments for file transfer services. The vulnerability's remote nature and lack of required authentication make it a significant threat if the server is exposed to untrusted networks, such as the internet.

For European organizations, this vulnerability poses a moderate risk, especially for those using PCMan FTP Server 2.0.7 in production environments exposed to external networks. Successful exploitation could allow attackers to execute arbitrary code on the affected server, potentially leading to unauthorized access, data theft, or disruption of services. Given that FTP servers often handle sensitive file transfers, compromise could result in leakage of confidential information or disruption of business operations. The medium CVSS score suggests limited but non-negligible impact on confidentiality, integrity, and availability. However, the lack of authentication and user interaction requirements increases the likelihood of exploitation if the server is reachable. European organizations in sectors such as manufacturing, logistics, or SMEs that rely on PCMan FTP Server for internal or external file transfers may be particularly vulnerable. Additionally, organizations with less mature cybersecurity practices or those that expose FTP services directly to the internet without adequate network segmentation or monitoring are at higher risk. The absence of known active exploits currently provides a window for remediation, but the public disclosure of exploit code could lead to increased attack attempts. The impact could be amplified if attackers leverage this vulnerability as an initial foothold for lateral movement or ransomware deployment within European networks.

1. Immediate mitigation should include restricting external network access to PCMan FTP Server instances, ideally limiting connections to trusted internal IP ranges or VPNs. 2. Disable or block the FTP TYPE command if possible, or implement input validation and filtering at network perimeter devices to detect and block malformed FTP commands. 3. Monitor FTP server logs and network traffic for unusual or malformed TYPE command requests that could indicate exploitation attempts. 4. Apply network segmentation to isolate FTP servers from critical infrastructure and sensitive data repositories to limit potential lateral movement. 5. Regularly update and patch PCMan FTP Server software once the vendor releases a security update addressing this vulnerability. 6. Consider migrating to more secure file transfer protocols such as SFTP or FTPS that provide encryption and stronger authentication mechanisms. 7. Employ intrusion detection/prevention systems (IDS/IPS) with signatures for known FTP buffer overflow exploits to detect and block attacks. 8. Conduct internal vulnerability scans and penetration tests to identify exposed FTP services and verify the effectiveness of implemented controls. 9. Educate IT staff about this vulnerability and ensure incident response plans include steps for handling potential exploitation scenarios related to FTP servers.