CVE-2006-5094 in phpBB XS
Summary
by MITRE
PHP remote file inclusion vulnerability in includes/functions_kb.php in the phpBB XS 2 (Spain version) allows remote attackers to execute arbitrary PHP code via a URL in the phpbb_root_path parameter, a different vector than CVE-2006-4780 or CVE-2006-4893.
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Analysis
by VulDB Data Team • 04/23/2026
The vulnerability identified as CVE-2006-5094 represents a critical remote file inclusion flaw within the phpBB XS 2 Spain version software suite. This vulnerability specifically affects the includes/functions_kb.php file and operates through the phpbb_root_path parameter, creating a pathway for malicious actors to inject and execute arbitrary PHP code on vulnerable systems. The flaw demonstrates the dangerous implications of improper input validation and dynamic path resolution in web applications, particularly those built on PHP frameworks where user-controllable parameters can directly influence file inclusion mechanisms. The vulnerability exists within the broader context of web application security where insufficient sanitization of user inputs can lead to catastrophic code execution scenarios.
The technical implementation of this vulnerability stems from the application's failure to properly validate or sanitize the phpbb_root_path parameter before using it in file inclusion operations. When an attacker provides a malicious URL as the value for this parameter, the application processes it without adequate verification, allowing the system to attempt to include and execute files from remote locations. This behavior aligns with CWE-98, which describes improper control of resource identifiers, and specifically manifests as a remote file inclusion vulnerability that operates outside the typical boundaries of local file inclusion attacks. The vulnerability's distinct nature from CVE-2006-4780 and CVE-2006-4893 indicates that attackers can leverage different vectors to achieve code execution, expanding the attack surface for potential exploitation.
The operational impact of this vulnerability extends beyond simple code execution to encompass complete system compromise and data exfiltration capabilities. Once successfully exploited, attackers can gain full control over the affected web server, potentially leading to persistent backdoor access, database compromise, and lateral movement within network environments. The vulnerability's remote nature means that attackers do not require local system access or credentials to exploit it, making it particularly dangerous for publicly accessible web applications. This type of vulnerability directly maps to ATT&CK technique T1190, which covers exploits for execution through remote file inclusion, and represents a critical threat to web application security where the attack surface includes user-controllable parameters that influence system behavior.
Mitigation strategies for CVE-2006-5094 must address both immediate remediation and long-term architectural improvements. The primary solution involves implementing strict input validation and sanitization for all user-controllable parameters, particularly those used in file inclusion contexts. Organizations should disable remote file inclusion capabilities entirely by configuring PHP settings to restrict include paths or by implementing proper parameter validation that rejects suspicious URL patterns. The implementation of input whitelisting for path parameters, combined with proper access controls and secure coding practices, provides comprehensive protection against this class of vulnerability. Additionally, regular security audits and vulnerability assessments should be conducted to identify similar flaws in other application components, as the vulnerability's root cause often appears in multiple locations within complex web applications. Security measures should also include network monitoring to detect unusual file inclusion patterns and intrusion detection systems configured to identify potential exploitation attempts targeting this specific vulnerability pattern.