CVE-2000-0296 in FCheck
Summary
by MITRE
fcheck allows local users to gain privileges by embedding shell metacharacters into file names that are processed by fcheck.
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Analysis
by VulDB Data Team • 04/21/2026
The vulnerability described in CVE-2000-0296 represents a classic privilege escalation flaw within the fcheck utility, which operates as a file checking tool typically used for verifying file integrity and permissions within Unix-like systems. This vulnerability specifically targets the way fcheck processes filenames that contain shell metacharacters, creating a dangerous condition where local attackers can manipulate the tool's behavior to execute arbitrary commands with elevated privileges. The issue stems from insufficient input validation and sanitization within the fcheck utility, allowing maliciously crafted filenames to be interpreted as shell commands rather than simple file identifiers.
The technical exploitation of this vulnerability occurs when a local user creates a file with a name containing shell metacharacters such as semicolons, pipes, or command substitution operators. When fcheck processes these filenames, it fails to properly escape or sanitize the input before passing it to shell commands, thereby enabling command injection attacks. This flaw directly relates to CWE-78, which describes improper neutralization of special elements used in OS commands, and CWE-20, which addresses improper input validation. The vulnerability operates at the system level where the fcheck utility runs with elevated privileges, typically as a setuid root program or through administrative access, making the privilege escalation particularly dangerous.
The operational impact of CVE-2000-0296 extends beyond simple local privilege escalation, as it can enable attackers to gain root access to compromised systems and potentially establish persistent backdoors. Once an attacker successfully exploits this vulnerability, they can execute arbitrary commands with full system privileges, allowing for complete system compromise. The attack vector is particularly concerning because it requires minimal user interaction beyond creating a specially named file, making it difficult to detect and prevent through standard monitoring. This vulnerability can be leveraged in conjunction with other attack techniques and aligns with ATT&CK tactics such as privilege escalation and persistence, where attackers use system-level tools to maintain control over compromised systems.
Mitigation strategies for CVE-2000-0296 require immediate patching of affected systems, as the vulnerability has been widely known and documented for over two decades. System administrators should ensure that all instances of the fcheck utility are updated to versions that properly sanitize input before shell command execution. Additional protective measures include implementing proper file naming conventions that prevent special characters in filenames, restricting write permissions to directories containing files processed by fcheck, and monitoring for unusual file creation patterns. Organizations should also consider implementing automated patch management systems to ensure all vulnerable utilities are promptly updated. The vulnerability serves as a critical reminder of the importance of input validation and proper sanitization in system utilities, particularly those operating with elevated privileges, and demonstrates how seemingly simple flaws can lead to complete system compromise.