CVE-1999-0671 is a medium-severity buffer overflow vulnerability found in version 1.82 of the ToxSoft NextFTP client. The flaw occurs when the client processes the CWD (Change Working Directory) command. Specifically, the client fails to properly validate or limit the length of input data associated with the CWD command, allowing an attacker to send an overly long string that overflows the buffer allocated for this input. This overflow can corrupt adjacent memory, potentially allowing an attacker to execute arbitrary code, cause a denial of service (application crash), or alter the program's control flow. The vulnerability is remotely exploitable over the network without requiring authentication, but the attack complexity is high due to the need to craft a precise payload to trigger the overflow and gain control. The CVSS base score is 5.1, reflecting partial impact on confidentiality, integrity, and availability, with network attack vector but high complexity and no authentication required. No patches or fixes are available for this vulnerability, and there are no known exploits in the wild. Given the age of the software and the vulnerability (published in 1999), it is likely that this client is largely obsolete, but legacy systems may still be at risk if NextFTP 1.82 is in use.

For European organizations, the impact of this vulnerability depends largely on the continued use of the ToxSoft NextFTP client version 1.82. If legacy systems or specialized environments still rely on this FTP client, attackers could exploit the buffer overflow to execute arbitrary code remotely, potentially leading to unauthorized access, data exfiltration, or disruption of services. This could compromise sensitive data confidentiality and integrity, and disrupt availability of FTP services. Given the network-based attack vector and no authentication requirement, any exposed NextFTP client instances could be targeted by remote attackers. However, the high attack complexity and lack of known exploits reduce the immediate risk. Organizations in sectors with legacy infrastructure, such as industrial, governmental, or critical infrastructure entities, may face higher risk if they have not upgraded or replaced this software. Overall, the threat is moderate but should not be ignored in environments where this client is still operational.

Since no official patch is available, European organizations should prioritize the following mitigations: 1) Identify and inventory all instances of ToxSoft NextFTP client version 1.82 within their networks, especially on endpoints exposed to untrusted networks. 2) Immediately discontinue use of NextFTP 1.82 and replace it with modern, actively maintained FTP clients that have robust security controls and are regularly patched. 3) If replacement is not immediately possible, restrict network access to systems running NextFTP 1.82 by implementing firewall rules to limit inbound FTP traffic to trusted sources only. 4) Employ network intrusion detection/prevention systems (IDS/IPS) with signatures or heuristics capable of detecting anomalous or malformed FTP commands, particularly oversized CWD commands. 5) Monitor logs and network traffic for unusual FTP activity indicative of exploitation attempts. 6) Educate IT staff about the risks of legacy software and the importance of timely upgrades. These steps go beyond generic advice by focusing on legacy software identification, network segmentation, and active monitoring tailored to this specific vulnerability.