CVE-2006-5223 in User Viewed Posts Tracker
Summary
by MITRE
PHP remote file inclusion vulnerability in includes/functions_user_viewed_posts.php in the Nivisec User Viewed Posts Tracker module 1.0 and earlier for phpBB allows remote attackers to execute arbitrary PHP code via a URL in the phpbb_root_path parameter.
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Analysis
by VulDB Data Team • 04/24/2026
The vulnerability described in CVE-2006-5223 represents a critical remote file inclusion flaw within the Nivisec User Viewed Posts Tracker module for phpBB version 1.0 and earlier. This vulnerability exists in the functions_user_viewed_posts.php file where user input is improperly handled, creating an avenue for attackers to inject malicious code through the phpbb_root_path parameter. The flaw stems from the module's failure to validate or sanitize input parameters before using them in file inclusion operations, making it susceptible to exploitation by remote threat actors who can manipulate the application's behavior through crafted URLs.
The technical implementation of this vulnerability aligns with CWE-88, which describes improper neutralization of special elements used in an expression, specifically in the context of remote file inclusion attacks. The vulnerability operates by allowing an attacker to supply a malicious URL through the phpbb_root_path parameter, which is then directly incorporated into a file inclusion statement without proper validation. This creates a scenario where an attacker can load arbitrary PHP files from remote servers, effectively enabling remote code execution on the target system. The attack vector is particularly dangerous because it leverages the legitimate file inclusion mechanisms of the phpBB platform, making it difficult to detect through standard security monitoring.
The operational impact of this vulnerability extends beyond simple code execution to encompass complete system compromise and potential data breaches. An attacker who successfully exploits this vulnerability can execute arbitrary PHP code on the affected server, potentially leading to unauthorized access to sensitive user data, modification of forum content, or establishment of persistent backdoors. The vulnerability affects all versions of the Nivisec User Viewed Posts Tracker module up to and including version 1.0, making it a widespread concern for phpBB installations that have not been updated or patched. The implications are particularly severe for forums that store sensitive user information or contain valuable content, as the compromise of one forum can lead to broader security implications for the entire platform.
Mitigation strategies for CVE-2006-5223 should focus on immediate patching and configuration hardening measures. The primary remediation involves upgrading to a patched version of the Nivisec User Viewed Posts Tracker module or removing the vulnerable module entirely from affected phpBB installations. Additionally, administrators should implement input validation and sanitization measures to prevent malicious URLs from being processed in the phpbb_root_path parameter. Security controls should include disabling remote file inclusion in php.ini configuration, implementing proper parameter validation, and establishing network-level restrictions to prevent access to potentially malicious URLs. Organizations should also consider implementing web application firewalls and intrusion detection systems to monitor for exploitation attempts and maintain comprehensive logging of file inclusion operations. This vulnerability demonstrates the critical importance of input validation and proper security practices in web application development, aligning with ATT&CK technique T1190 for exploitation of remote services and T1059 for execution of malicious code through web applications.