CVE-2000-0176 in Serv-U
Summary
by MITRE
The default configuration of Serv-U 2.5d and earlier allows remote attackers to determine the real pathname of the server by requesting a URL for a directory or file that does not exist.
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Analysis
by VulDB Data Team • 10/19/2025
The vulnerability identified as CVE-2000-0176 represents a significant information disclosure weakness in Serv-U FTP server versions 2.5d and earlier. This flaw stems from the software's default configuration which fails to properly sanitize or obscure directory traversal requests, allowing unauthorized users to infer the actual filesystem structure of the server. The vulnerability specifically manifests when remote attackers submit requests for non-existent files or directories, enabling them to receive responses that inadvertently reveal the underlying pathname structure of the server's file system.
This technical weakness falls under the category of information disclosure vulnerabilities and can be categorized as CWE-200, which deals with the exposure of sensitive information. The flaw operates at the application layer where the FTP server's response handling mechanism does not adequately filter or mask the true filesystem paths that are being accessed. When a user requests a resource that does not exist, the server's default behavior returns error messages that contain the actual path information, thereby leaking directory structures that should remain hidden from external parties. This exposure provides attackers with valuable reconnaissance information that could facilitate more sophisticated attacks.
The operational impact of this vulnerability extends beyond simple information disclosure, as it creates a foundation for further exploitation attempts. Attackers can use the leaked path information to plan targeted attacks against specific directories or files, potentially identifying sensitive data locations or system components. The vulnerability affects the principle of least privilege and information hiding, as it violates the security assumption that the server's internal filesystem structure should remain confidential. This information leakage can be particularly damaging in environments where the FTP server hosts sensitive data or where the directory structure contains clues about the broader system architecture.
The implications of this vulnerability align with several ATT&CK techniques including T1083 (File and Directory Discovery) and T1592 (Gather Victim Host Information). Security practitioners should recognize this as a configuration management issue that highlights the importance of proper security hardening practices. The vulnerability demonstrates how default installations can introduce security weaknesses that require explicit configuration changes to address. Organizations should implement proper access controls and ensure that all server responses are sanitized to prevent the disclosure of internal filesystem paths. Mitigation strategies include updating to newer versions of Serv-U that address this issue, implementing proper input validation, and configuring the server to return generic error messages that do not reveal path information. Regular security audits and configuration reviews should be conducted to prevent similar issues from arising in other services or applications within the network infrastructure.