CVE-1999-0076 describes a buffer overflow vulnerability in the wu-ftpd (Washington University FTP daemon) software, specifically triggered by the PASV command. The PASV command in FTP is used to initiate passive mode data transfers, where the server opens a port and waits for the client to connect. In this vulnerability, the input handling of the PASV command does not properly validate or limit the size of the input buffer, leading to a buffer overflow condition. This overflow causes the wu-ftpd process to crash and produce a core dump, resulting in a denial of service (DoS) condition. The vulnerability does not appear to allow for code execution or privilege escalation, as indicated by the CVSS vector (Confidentiality: None, Integrity: None, Availability: Partial). The vulnerability was published in 1997 and has a medium severity score of 5.0. No patches are available, and there are no known exploits in the wild. Given the age of the vulnerability and the product, it is likely that modern systems have moved away from wu-ftpd or have mitigated this risk through other means. However, legacy systems or those still running wu-ftpd could be vulnerable to DoS attacks via crafted PASV commands.

For European organizations, the primary impact of this vulnerability is a potential denial of service on FTP servers running vulnerable versions of wu-ftpd. This could disrupt file transfer services, impacting business operations that rely on FTP for data exchange. While the vulnerability does not compromise confidentiality or integrity, the availability impact could affect sectors that depend on FTP for critical workflows, such as manufacturing, logistics, or government agencies. Given the age of the vulnerability and the lack of known exploits, the risk is likely low for most organizations using modern FTP solutions. However, organizations with legacy infrastructure or embedded systems running wu-ftpd could face service interruptions if targeted. Additionally, disruption of FTP services could indirectly affect compliance with data handling or operational continuity regulations within the EU.

Specific mitigation recommendations include: 1) Identify and inventory all FTP servers running wu-ftpd within the organization, especially legacy systems. 2) Where possible, replace wu-ftpd with modern, actively maintained FTP server software that includes security patches and improved input validation. 3) If replacement is not feasible, implement network-level protections such as firewall rules to restrict access to FTP services only to trusted IP addresses and networks. 4) Monitor FTP server logs for unusual PASV command usage or repeated crashes that may indicate exploitation attempts. 5) Employ intrusion detection/prevention systems (IDS/IPS) with signatures or heuristics to detect malformed FTP commands. 6) Consider disabling the PASV command if passive mode FTP is not required, or restrict FTP usage to active mode only. 7) Regularly review and update legacy systems to reduce exposure to known vulnerabilities. These steps go beyond generic advice by focusing on legacy system identification, network access controls, and operational monitoring tailored to this specific vulnerability.