CVE-1999-1165 in fingerd
Summary
by MITRE
GNU fingerd 1.37 does not properly drop privileges before accessing user information, which could allow local users to (1) gain root privileges via a malicious program in the .fingerrc file, or (2) read arbitrary files via symbolic links from .plan, .forward, or .project files.
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Analysis
by VulDB Data Team • 04/19/2026
The vulnerability identified as CVE-1999-1165 affects GNU fingerd version 1.37, a network service that provides user information lookup functionality over the network. This issue represents a classic privilege escalation flaw that demonstrates poor security implementation in daemon processes. The fingerd service traditionally runs with elevated privileges to access system user information, but fails to properly drop these privileges before processing user-specific configuration files. This design flaw creates a critical security gap that can be exploited by local attackers to gain unauthorized access to system resources.
The technical implementation of this vulnerability stems from the fingerd daemon's failure to properly implement privilege separation mechanisms. When processing user requests, the service reads configuration files such as .fingerrc, .plan, .forward, and .project which are typically located in user home directories. These files can contain arbitrary commands or symbolic links that, when executed with elevated privileges, allow malicious actors to execute code with root permissions. The vulnerability specifically manifests when the daemon does not properly drop root privileges before reading these user-controlled files, creating a path for privilege escalation attacks. This flaw directly relates to CWE-276, which addresses improper privileges, and represents a common pattern in Unix-like systems where services fail to properly implement privilege separation.
The operational impact of this vulnerability is severe and multifaceted, encompassing both local privilege escalation and information disclosure capabilities. Local users can exploit this vulnerability to gain root access through malicious .fingerrc files that execute arbitrary commands with elevated privileges, effectively bypassing system security controls. Additionally, attackers can leverage symbolic links within .plan, .forward, or .project files to read arbitrary system files that would normally be restricted. This creates a dual threat scenario where attackers can both escalate privileges and access sensitive system information. The vulnerability is particularly dangerous because it requires no network access and can be exploited by any local user, making it a significant concern for system administrators who may not properly monitor local user activities.
Mitigation strategies for CVE-1999-1165 should focus on immediate privilege separation implementation and system hardening measures. The primary recommendation involves ensuring that fingerd services properly drop root privileges before processing user configuration files, which can be achieved through proper implementation of setuid/setgid mechanisms or privilege separation libraries. System administrators should consider disabling the fingerd service entirely if it is not required, as it represents an unnecessary attack surface. Additional mitigations include implementing proper file permissions and access controls on user configuration files, monitoring for suspicious symbolic link usage, and conducting regular security audits of daemon processes. The vulnerability also highlights the importance of following the principle of least privilege and implementing proper privilege separation, which aligns with ATT&CK technique T1068 for privilege escalation and T1083 for file and directory discovery. Organizations should also consider implementing process monitoring to detect unauthorized privilege escalation attempts and ensure that all system services properly implement proper privilege separation mechanisms to prevent similar vulnerabilities from occurring in other applications.