CVE-1999-0259 in cfingerd
Summary
by MITRE
cfingerd lists all users on a system via search.**@target.
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Analysis
by VulDB Data Team • 04/16/2026
The vulnerability described in CVE-1999-0259 affects the cfingerd daemon, which is a finger protocol implementation commonly found on unix-like systems. This daemon provides a service that allows remote users to query user information on a system, typically through the standard finger protocol port 79. The core flaw lies in the implementation of the search functionality within cfingerd, which permits unauthorized access to complete user listings on the target system. When a remote attacker sends a search query to the finger daemon, the system responds by enumerating all valid user accounts present on the host, effectively providing a comprehensive directory of system users to any potential malicious actor.
This vulnerability represents a classic information disclosure issue that can be categorized under CWE-200, which deals with information exposure. The technical flaw stems from inadequate input validation and access control mechanisms within the cfingerd service. The daemon fails to properly authenticate or authorize search requests, allowing any remote user to submit queries that return complete user account information. The attack vector is straightforward and requires minimal technical expertise, as it only necessitates connecting to the finger service and submitting a search pattern that triggers the user enumeration functionality. This behavior violates fundamental security principles by exposing system user information without proper authorization checks, creating a significant reconnaissance opportunity for attackers.
The operational impact of this vulnerability extends beyond simple user enumeration, as it provides attackers with critical information for subsequent attack phases. Once an attacker has obtained a complete list of valid usernames, they can proceed with targeted password guessing attacks, brute force attempts, or social engineering campaigns. The vulnerability enables passive reconnaissance that can be combined with other techniques to escalate privileges or gain unauthorized access to system resources. According to ATT&CK framework, this vulnerability maps to T1087.001 - Account Discovery: Local Account and T1592.002 - Technique for reconnaissance activities involving user enumeration. The exposure of user accounts creates additional attack surface and can facilitate further compromise of the system through credential-based attacks or privilege escalation attempts.
Mitigation strategies for CVE-1999-0259 should focus on both immediate and long-term solutions. The most effective immediate fix involves disabling the finger service entirely, as it is largely obsolete and poses significant security risks. Organizations should implement network segmentation to restrict access to finger service ports, ensuring that only authorized systems can reach the service. When the finger service must remain operational, administrators should configure proper access controls and implement rate limiting to prevent excessive user enumeration attempts. Additionally, system administrators should regularly audit user accounts and implement strong authentication mechanisms to reduce the impact of any compromised credentials. The vulnerability highlights the importance of disabling unnecessary network services and maintaining up-to-date security configurations as outlined in security standards such as NIST SP 800-53 and ISO 27001 controls for access control and system hardening.