CVE-2000-0860 in PHP
Summary
by MITRE
The file upload capability in PHP versions 3 and 4 allows remote attackers to read arbitrary files by setting hidden form fields whose names match the names of internal PHP script variables.
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Analysis
by VulDB Data Team • 10/12/2025
The vulnerability described in CVE-2000-0860 represents a critical security flaw in early versions of PHP that fundamentally compromised the integrity of file upload mechanisms. This issue affected PHP versions 3 and 4, which were widely deployed during the late 1990s and early 2000s, making it particularly dangerous as it impacted a large portion of web applications. The vulnerability stems from insufficient input validation and improper handling of form field names during file upload processes, creating a pathway for attackers to manipulate internal PHP script variables through crafted hidden form fields.
The technical exploitation of this vulnerability occurs through a sophisticated manipulation of HTTP form data where attackers craft hidden input fields with names that correspond to internal PHP script variables. When PHP processes these form fields, it inadvertently treats the attacker-controlled values as if they were legitimate internal variables, allowing unauthorized access to file system resources. This flaw operates at the core of PHP's variable handling mechanism, specifically targeting how the interpreter processes form data and assigns values to internal variables during script execution. The vulnerability is classified under CWE-20 as "Improper Input Validation" and represents a form of parameter pollution that bypasses normal security controls.
The operational impact of CVE-2000-0860 extends far beyond simple file reading capabilities, as it provides attackers with the ability to access sensitive system files, configuration data, and potentially execute arbitrary code. This vulnerability aligns with ATT&CK technique T1566.001 for "Phishing: Spearphishing Attachment" and T1059.007 for "Command and Scripting Interpreter: Python" as attackers could leverage this flaw to gain access to system resources and potentially escalate privileges. The ability to read arbitrary files means that attackers could access database credentials, application configuration files, and other sensitive information stored on the server, fundamentally compromising the confidentiality and integrity of web applications.
Organizations affected by this vulnerability should implement immediate mitigations including upgrading to PHP versions 5.0 or later where this vulnerability has been addressed through improved input validation and proper handling of form variables. The recommended approach involves implementing strict input validation on all file upload mechanisms, ensuring that form field names are sanitized and validated against a whitelist of acceptable values. Additionally, administrators should configure web servers to restrict access to sensitive directories and implement proper file type validation to prevent malicious uploads. Security measures should include monitoring for unusual file access patterns and implementing web application firewalls to detect and block suspicious form submissions. The vulnerability demonstrates the importance of proper input sanitization and the dangers of trusting user-supplied data without adequate validation, serving as a critical lesson in secure coding practices for web application development.
This vulnerability also highlights the broader implications of improper variable handling in scripting languages and underscores the necessity of following secure coding guidelines as outlined in OWASP Top Ten and NIST Cybersecurity Framework. The flaw represents a classic example of how seemingly minor implementation details in web application frameworks can create significant security risks when not properly addressed through comprehensive security testing and validation processes.