CVE-2000-0462 in NetBSD
Summary
by MITRE
ftpd in NetBSD 1.4.2 does not properly parse entries in /etc/ftpchroot and does not chroot the specified users, which allows those users to access other files outside of their home directory.
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Analysis
by VulDB Data Team • 04/21/2026
The vulnerability described in CVE-2000-0462 represents a critical access control flaw in the ftpd service component of NetBSD 1.4.2 systems. This issue stems from improper parsing of entries within the /etc/ftpchroot configuration file which is designed to restrict ftp users to their home directories through the chroot mechanism. The flaw allows authenticated ftp users to escape their designated chroot boundaries and access files and directories outside their intended home directories, effectively bypassing the security controls that should isolate user sessions.
The technical implementation of this vulnerability resides in the ftpd daemon's parsing logic for the /etc/ftpchroot file which contains user-to-home directory mappings. When the ftpd service processes user authentication, it should verify that the specified user entries in /etc/ftpchroot are properly formatted and correctly parsed to enforce chroot restrictions. However, the parsing implementation contains a flaw that prevents proper validation of these entries, resulting in users being granted broader file system access than intended. This represents a classic case of improper input validation and privilege escalation through configuration file manipulation.
The operational impact of this vulnerability extends beyond simple unauthorized file access, as it fundamentally undermines the security model of the ftp service. An attacker who gains access to an ftp account can exploit this vulnerability to traverse the file system and potentially access sensitive system files, configuration data, or other users' data. The vulnerability is particularly dangerous because it affects the core chroot functionality that serves as a primary security boundary for ftp users. This flaw aligns with CWE-22 - Improper Limitation of a Pathname to a Restricted Directory, which addresses the issue of insufficient validation of file paths and directory access controls.
The security implications of this vulnerability are severe and can be categorized under multiple ATT&CK techniques including privilege escalation and lateral movement. Attackers can leverage this weakness to establish persistent access to system resources while bypassing the fundamental security boundary imposed by chroot operations. The vulnerability also demonstrates poor separation of privileges, as users who should be restricted to their home directories can access the entire system file structure, potentially enabling further exploitation such as privilege escalation to root access or data exfiltration.
Mitigation strategies for this vulnerability should include immediate patching of the NetBSD 1.4.2 system to a patched version that properly implements ftpchroot parsing. System administrators should also implement additional monitoring of ftp access patterns and file system access attempts from ftp users. The configuration file /etc/ftpchroot should be carefully reviewed and validated to ensure proper formatting before deployment. Additionally, implementing network segmentation and restricting ftp access to trusted networks can reduce the attack surface. Organizations should also consider implementing alternative authentication mechanisms such as sftp or scp for secure file transfers, as these protocols provide better built-in security controls than traditional ftp implementations. The vulnerability highlights the importance of proper input validation and configuration file parsing in security-critical services, emphasizing the need for comprehensive testing of access control mechanisms.