CVE-2025-4159 is a buffer overflow vulnerability identified in PCMan FTP Server versions 2.0.0 through 2.0.7. The flaw resides in an unspecified functionality within the GLOB Command Handler component of the FTP server. Buffer overflow vulnerabilities occur when a program writes more data to a buffer than it can hold, potentially overwriting adjacent memory. This can lead to arbitrary code execution, crashes, or other unpredictable behavior. In this case, the vulnerability can be exploited remotely without requiring authentication or user interaction, as indicated by the CVSS vector (AV:N/AC:L/AT:N/UI:N/PR:N). The vulnerability has a CVSS 4.0 base score of 6.9, categorized as medium severity, reflecting limited impact on confidentiality, integrity, and availability (each rated low). The scope is unchanged, meaning the vulnerability affects only the vulnerable component and does not propagate to other components. Although no public exploit is currently known to be in the wild, the exploit code has been disclosed publicly, increasing the risk of exploitation. The vulnerability affects all versions up to 2.0.7, and no official patches or mitigations have been linked or published at this time. The PCMan FTP Server is a lightweight FTP server software commonly used in small to medium-sized environments for file transfer services. The GLOB Command Handler processes commands related to filename pattern matching, and improper handling of these commands leads to the buffer overflow condition. Attackers could leverage this vulnerability to execute arbitrary code remotely, potentially gaining control over the affected server or causing denial of service by crashing the service. Given the ease of exploitation (no authentication or user interaction required) and remote attack vector, this vulnerability poses a tangible risk to organizations running vulnerable versions of PCMan FTP Server.

For European organizations, the impact of this vulnerability depends on the prevalence of PCMan FTP Server deployments within their IT infrastructure. Organizations using this FTP server for file transfer services may face risks of unauthorized remote code execution or service disruption. This could lead to data breaches, loss of data integrity, or operational downtime. Sectors relying on FTP for critical file exchanges, such as manufacturing, logistics, or government agencies, could experience operational disruptions or data compromise. The medium CVSS score reflects limited confidentiality, integrity, and availability impacts individually, but combined effects could be significant if exploited in targeted attacks. Additionally, since the exploit is publicly disclosed, opportunistic attackers may attempt automated scanning and exploitation campaigns, increasing exposure. The lack of authentication requirement means that external attackers can attempt exploitation without prior access, raising the threat level for internet-facing FTP servers. Organizations with inadequate network segmentation or monitoring may be particularly vulnerable to lateral movement or further compromise following exploitation. Overall, the vulnerability could facilitate initial footholds in networks, data exfiltration, or ransomware deployment if exploited successfully.

1. Immediate mitigation should include disabling the GLOB command functionality if configurable or restricting access to the FTP server to trusted internal networks only, preventing exposure to the internet. 2. Monitor network traffic for unusual FTP command patterns or anomalous connections targeting the FTP server, leveraging IDS/IPS signatures or custom detection rules focusing on GLOB command misuse. 3. Implement strict firewall rules to limit FTP server access to known IP addresses and enforce network segmentation to isolate FTP servers from critical infrastructure. 4. If possible, upgrade to a newer, patched version of PCMan FTP Server once available; in the absence of official patches, consider migrating to alternative FTP server software with active security support. 5. Employ application-layer gateways or FTP proxies that can sanitize or block malicious FTP commands, including malformed GLOB commands. 6. Conduct regular vulnerability scanning and penetration testing focused on FTP services to detect exploitation attempts. 7. Maintain comprehensive logging and alerting on FTP server activity to enable rapid incident response. 8. Educate IT staff about this vulnerability and ensure timely application of security advisories related to PCMan FTP Server.