CVE-2025-5636 is a buffer overflow vulnerability identified in PCMan FTP Server version 2.0.7, specifically within the SET Command Handler component. This vulnerability arises due to improper handling of input data, allowing an attacker to send crafted commands that overflow the buffer allocated for processing the SET command. Buffer overflow vulnerabilities can lead to arbitrary code execution, denial of service, or system crashes. The vulnerability is remotely exploitable without requiring authentication or user interaction, as indicated by the CVSS vector (AV:N/AC:L/PR:N/UI:N). The CVSS score of 6.9 categorizes it as a medium severity issue, reflecting the potential for partial impact on confidentiality, integrity, and availability, but with some limitations in scope or impact. Although no known exploits are currently reported in the wild, the public disclosure of the vulnerability increases the risk of exploitation attempts. The absence of available patches or mitigation links at the time of publication suggests that affected organizations must proactively implement defensive measures. The vulnerability does not require privileges or user interaction, making it more accessible to attackers scanning for vulnerable FTP servers. Given the critical nature of buffer overflows in network-facing services, successful exploitation could allow attackers to execute arbitrary code on the server, potentially leading to full system compromise or lateral movement within a network.

For European organizations, the exploitation of CVE-2025-5636 could have significant consequences, especially for those relying on PCMan FTP Server 2.0.7 for file transfer services. Compromise of FTP servers can lead to unauthorized access to sensitive data, disruption of business operations, and potential footholds for further attacks within corporate networks. Given the FTP server’s role in data exchange, attackers could intercept or manipulate files, impacting data integrity and confidentiality. Additionally, the ability to execute arbitrary code remotely could allow attackers to deploy malware, ransomware, or establish persistent access. Organizations in sectors such as finance, manufacturing, and government, which often handle sensitive or regulated data, may face compliance violations and reputational damage if exploited. The medium severity rating suggests that while the vulnerability is serious, exploitation may require specific conditions or may not lead to full system compromise in all cases. However, the lack of authentication and user interaction requirements increases the risk of automated exploitation attempts, making timely mitigation critical.

1. Immediate upgrade or patching: Organizations should monitor PCMan’s official channels for patches addressing this vulnerability and apply them promptly once available. 2. Network-level controls: Restrict access to FTP servers using firewalls or network segmentation to limit exposure to untrusted networks, especially the internet. 3. Disable or restrict the SET command: If possible, configure the FTP server to disable or restrict the SET command handler to prevent exploitation of the vulnerable component. 4. Implement intrusion detection/prevention systems (IDS/IPS): Deploy IDS/IPS solutions with updated signatures to detect and block attempts to exploit this buffer overflow. 5. Monitor logs and network traffic: Establish enhanced monitoring for unusual FTP commands or traffic patterns indicative of exploitation attempts. 6. Consider alternative secure file transfer protocols: Where feasible, migrate from FTP to more secure protocols such as SFTP or FTPS, which provide encryption and improved security controls. 7. Conduct vulnerability scanning: Regularly scan internal and external assets to identify instances of PCMan FTP Server 2.0.7 and verify remediation status. These measures go beyond generic advice by focusing on command-level restrictions, network segmentation, and proactive monitoring tailored to the nature of this vulnerability.