CVE-2006-5804 in Advanced Guestbook
Summary
by MITRE
PHP remote file inclusion vulnerability in admin.php in Advanced Guestbook 2.3.1 allows remote attackers to execute arbitrary PHP code via a URL in the include_path parameter.
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Analysis
by VulDB Data Team • 04/26/2026
The vulnerability described in CVE-2006-5804 represents a critical remote file inclusion flaw within the Advanced Guestbook 2.3.1 web application, specifically affecting the admin.php script. This issue arises from improper input validation and sanitization mechanisms that fail to properly restrict user-supplied data from being directly incorporated into file inclusion operations. The vulnerability exists because the application accepts user-provided input through the include_path parameter and uses it without adequate sanitization or validation, creating an avenue for malicious actors to inject arbitrary PHP code into the execution flow.
The technical nature of this flaw aligns with CWE-88, which describes improper neutralization of special elements used in an OS command, and more specifically with CWE-94, which addresses the execution of arbitrary code or commands. The vulnerability operates by allowing attackers to manipulate the include_path parameter to reference remote malicious files that contain PHP code. When the admin.php script processes this parameter, it attempts to include the specified file path, thereby executing the malicious code within the context of the web server's privileges. This type of vulnerability falls under the ATT&CK technique T1190, which describes the use of remote file inclusion to execute malicious code on target systems.
The operational impact of this vulnerability is severe and encompasses multiple attack vectors that can lead to complete system compromise. An attacker can leverage this flaw to execute arbitrary commands on the affected server, potentially gaining full control over the web application and underlying system. The remote nature of the vulnerability means that attackers do not require local access or credentials to exploit it, making it particularly dangerous for publicly accessible web applications. Additionally, the vulnerability can be exploited to establish persistent backdoors, exfiltrate sensitive data, or use the compromised server as a launching point for further attacks against internal networks. The execution of arbitrary PHP code also allows for privilege escalation and information disclosure attacks that can compromise the confidentiality and integrity of the affected system.
Mitigation strategies for CVE-2006-5804 must address both the immediate vulnerability and broader security practices to prevent similar issues. The most effective immediate solution involves implementing strict input validation and sanitization for all user-supplied parameters, particularly those used in file inclusion operations. Web applications should employ whitelisting mechanisms that restrict file inclusion to predefined, trusted paths rather than allowing arbitrary user input. Additionally, the disable_functions directive in php.ini should be configured to prevent execution of dangerous functions such as eval, exec, and system. Security headers and proper error handling should also be implemented to prevent information leakage that could aid attackers in exploiting similar vulnerabilities. Organizations should also consider implementing web application firewalls and regular security audits to detect and prevent exploitation attempts. The vulnerability demonstrates the importance of following secure coding practices and the principle of least privilege in web application development, where input validation should be implemented at multiple layers of the application architecture to prevent such critical flaws from being exploited in production environments.