CVE-2025-5331 is a buffer overflow vulnerability identified in PCMan FTP Server version 2.0.7, specifically within the NLST command handler component. The NLST command in FTP is used to list directory contents, and improper handling of this command's input can lead to a buffer overflow condition. This vulnerability allows an unauthenticated remote attacker to send specially crafted NLST commands to the server, triggering the buffer overflow. The overflow can corrupt memory, potentially leading to arbitrary code execution, denial of service, or system instability. The vulnerability is remotely exploitable without requiring user interaction or authentication, increasing its risk profile. Although the CVSS v4.0 base score is 6.9, categorized as medium severity, the potential for remote code execution elevates the threat significance. No patches or fixes have been publicly linked yet, and no known exploits are reported in the wild at this time. However, the public disclosure of the vulnerability details increases the risk of exploitation attempts. The vulnerability affects only version 2.0.7 of PCMan FTP Server, which is a lightweight FTP server software often used in small to medium-sized environments. The lack of authentication and user interaction requirements combined with network attack vector (AV:N) means attackers can attempt exploitation over the internet or internal networks where the server is reachable. The vulnerability impacts confidentiality, integrity, and availability due to the possibility of arbitrary code execution or service disruption.

For European organizations, the impact of this vulnerability can be significant, especially for those relying on PCMan FTP Server 2.0.7 for file transfer services. Exploitation could lead to unauthorized access to sensitive files, disruption of file transfer services, or full compromise of the underlying server system. This could result in data breaches, operational downtime, and potential lateral movement within networks. Given the FTP server's role in transferring files, confidentiality and integrity of data are at risk. Organizations in sectors such as finance, healthcare, manufacturing, and government, where FTP servers are used for critical file exchanges, could face operational and reputational damage. Additionally, the vulnerability's remote exploitability without authentication increases the attack surface, especially if the FTP server is exposed to the internet. European organizations with less mature patch management or legacy systems may be particularly vulnerable. The absence of a patch at the time of disclosure necessitates immediate risk mitigation to prevent exploitation. Furthermore, compliance with European data protection regulations (e.g., GDPR) could be jeopardized if data confidentiality is compromised due to this vulnerability.

1. Immediate mitigation should include restricting external network access to the PCMan FTP Server, ideally limiting connections to trusted internal networks or VPNs. 2. Disable or restrict the use of the NLST command if possible, or configure the FTP server to limit command input sizes to prevent buffer overflow conditions. 3. Monitor network traffic for unusual or malformed NLST commands that could indicate exploitation attempts. 4. Employ network-level protections such as Web Application Firewalls (WAFs) or Intrusion Prevention Systems (IPS) with custom rules to detect and block exploit attempts targeting the NLST command. 5. Regularly audit and inventory FTP server versions across the organization to identify and isolate vulnerable instances. 6. Engage with the vendor or community to obtain patches or updates as soon as they become available and plan for prompt deployment. 7. Consider migrating to more secure file transfer protocols (e.g., SFTP or FTPS) that provide encryption and improved security controls. 8. Implement robust logging and alerting on FTP servers to detect anomalous activities early. 9. Educate IT staff about this vulnerability and ensure incident response plans include steps for potential exploitation scenarios.