CVE-2000-0059 in PHP
Summary
by MITRE
PHP3 with safe_mode enabled does not properly filter shell metacharacters from commands that are executed by popen, which could allow remote attackers to execute commands.
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Analysis
by VulDB Data Team • 10/19/2025
The vulnerability described in CVE-2000-0059 represents a critical security flaw in PHP3 versions when operating in safe_mode execution context. This issue stems from improper sanitization of shell metacharacters within command execution functions, specifically affecting the popen function which is used to open process pointers for executing system commands. The vulnerability occurs when PHP3 processes user-supplied input through the popen function while safe_mode is enabled, creating a scenario where malicious input can bypass intended security restrictions.
The technical flaw resides in the inadequate filtering mechanism that fails to properly sanitize special shell characters such as semicolons, ampersands, pipes, and backticks that could be used to chain commands or manipulate execution flow. When safe_mode is enabled, PHP3 should restrict command execution to prevent unauthorized access, but this vulnerability demonstrates a weakness in the input validation process that allows attackers to inject malicious shell commands through the popen function. The flaw essentially creates a command injection vector that operates despite the presence of safety mechanisms designed to prevent such exploits.
From an operational impact perspective, this vulnerability enables remote attackers to execute arbitrary system commands on affected servers, potentially leading to complete system compromise. An attacker could leverage this weakness to gain unauthorized access to the underlying operating system, escalate privileges, or execute malicious code. The vulnerability is particularly dangerous because it operates within the context of safe_mode, which users might expect to provide additional protection against command execution attacks, thereby creating a false sense of security. The implications extend beyond simple command execution to include potential data breaches, system infiltration, and unauthorized access to sensitive information stored on the affected systems.
The vulnerability aligns with CWE-78, which specifically addresses improper neutralization of special elements used in OS commands, and relates to ATT&CK technique T1059.007 for command and scripting interpreter. Organizations should implement immediate mitigations including upgrading to patched versions of PHP3, implementing strict input validation and sanitization for all user-supplied data, and avoiding the use of vulnerable functions like popen when possible. Additional protective measures include implementing proper network segmentation, monitoring for suspicious command execution patterns, and establishing robust access controls to limit potential exploitation. The vulnerability underscores the importance of comprehensive security testing and the need for thorough validation of security mechanisms, particularly those designed to prevent command injection attacks in web applications.