CVE-2001-0256 in FTP++ Server
Summary
by MITRE
FaSTream FTP++ Server 2.0 allows remote attackers to cause a denial of service, and possibly execute arbitrary commands, via a long username.
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Analysis
by VulDB Data Team • 10/07/2025
The vulnerability identified as CVE-2001-0256 affects the FaSTream FTP++ Server version 2.0, representing a critical security flaw that exposes the system to remote exploitation. This issue stems from inadequate input validation within the server's authentication mechanism, specifically when processing username parameters. The vulnerability manifests when a remote attacker submits an excessively long username string to the FTP server, which can trigger unexpected behavior in the application's memory handling routines.
This flaw falls under the category of buffer overflow vulnerabilities, which are categorized as CWE-121 in the Common Weakness Enumeration framework. The technical implementation of the FTP server fails to properly validate the length of incoming username data, allowing malicious input to exceed the allocated buffer space. When the server attempts to process this oversized username, it can cause memory corruption that leads to application instability and potential arbitrary code execution. The vulnerability demonstrates characteristics of both denial of service and remote code execution capabilities, making it particularly dangerous in networked environments where FTP services are exposed to untrusted users.
The operational impact of this vulnerability extends beyond simple service disruption, as it can enable attackers to gain unauthorized access to the underlying system. When exploited successfully, the buffer overflow can be leveraged to execute arbitrary commands with the privileges of the FTP service account, potentially leading to complete system compromise. This represents a significant risk in environments where the FTP server operates with elevated privileges or has access to sensitive data repositories. The vulnerability affects systems running the specific FaSTream FTP++ Server 2.0 version and requires immediate attention from system administrators to prevent potential exploitation.
Mitigation strategies for this vulnerability should include immediate patching of the affected FTP server software to address the buffer overflow in username handling. Organizations should implement network segmentation to limit access to FTP services and deploy intrusion detection systems to monitor for suspicious username length patterns. The use of alternative authentication methods such as SFTP or FTPS can provide additional security layers while the permanent fix is implemented. System administrators should also consider implementing input validation rules at network boundaries and regularly review server configurations to ensure that unnecessary services remain disabled. According to ATT&CK framework tactics, this vulnerability aligns with T1210 (Exploitation of Remote Services) and T1059 (Command and Scripting Interpreter) techniques, highlighting the need for comprehensive defensive measures that address both service hardening and network monitoring capabilities.