CVE-2006-5471 in PHP Developer Library
Summary
by MITRE
PHP remote file inclusion vulnerability in example/lib/grid3.lib.php in Softerra PHP Developer Library 1.5.3 and earlier allows remote attackers to execute arbitrary PHP code via a URL in the (1) cfg_dir and (2) lib_dir parameters.
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Analysis
by VulDB Data Team • 04/25/2026
The vulnerability identified as CVE-2006-5471 represents a critical remote file inclusion flaw within the Softerra PHP Developer Library version 1.5.3 and earlier releases. This issue resides in the example/lib/grid3.lib.php component where improper input validation allows malicious actors to inject arbitrary URLs into parameter fields. The vulnerability specifically affects the cfg_dir and lib_dir parameters, which are susceptible to manipulation through user-supplied input without adequate sanitization measures. This flaw enables remote attackers to execute arbitrary PHP code on the affected system by leveraging the remote file inclusion mechanism inherent in PHP's include or require functions when these parameters are not properly validated. The vulnerability directly maps to CWE-88, which describes improper neutralization of special elements used in an expression, specifically in the context of argument injection. Attackers can exploit this weakness by crafting malicious URLs that point to remote servers hosting malicious PHP scripts, effectively bypassing local security controls and gaining unauthorized execution privileges.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with a pathway to establish persistent access to affected systems. When exploited, the vulnerability allows for complete system compromise through remote code execution, potentially enabling attackers to install backdoors, exfiltrate sensitive data, or launch further attacks against network infrastructure. The attack vector leverages the trust model inherent in PHP's include functions, where the application blindly includes files specified through user input without proper validation. This vulnerability aligns with ATT&CK technique T1190, which describes the use of remote services for initial access and execution, and T1059.007, which covers the use of PHP for execution purposes. The flaw is particularly dangerous because it requires no authentication and can be exploited through simple HTTP requests, making it highly attractive to automated attack tools. The vulnerability exists due to insufficient input validation and sanitization practices, where the application fails to properly verify that the input parameters contain only expected values or paths within the intended directory structure.
Mitigation strategies for this vulnerability must address both immediate remediation and long-term architectural improvements. The primary fix involves implementing strict input validation and sanitization for all user-supplied parameters that are used in file inclusion operations. This includes validating that input parameters contain only expected values, rejecting any input that contains URLs or protocol schemes, and ensuring that all file paths are properly sanitized before being passed to include or require functions. Organizations should also implement proper parameter validation by using allowlists of acceptable values rather than denylists, which are inherently insecure. The recommended approach includes configuring PHP with appropriate security settings such as disabling remote file inclusion through the disable_functions directive and setting appropriate open_basedir restrictions. Additionally, implementing proper input validation frameworks and conducting regular security code reviews can prevent similar vulnerabilities from occurring in future development cycles. The remediation process should also include updating to the latest version of the Softerra PHP Developer Library where this vulnerability has been addressed, as well as implementing network-level protections such as web application firewalls to detect and block malicious requests attempting to exploit this vulnerability. The vulnerability demonstrates the critical importance of secure coding practices and input validation in preventing remote code execution attacks that can lead to complete system compromise.