CVE-2006-5731 in Lithium CMS
Summary
by MITRE
Directory traversal vulnerability in classes/index.php in Lithium CMS 4.04c and earlier allows remote attackers to include and execute arbitrary local files via a .. (dot dot) in the siteconf[curl] parameter, as demonstrated by a POST to news/comment.php containing PHP code, which is stored under db/comments/news/ and included by classes/index.php.
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Analysis
by VulDB Data Team • 04/26/2026
The vulnerability described in CVE-2006-5731 represents a critical directory traversal flaw within the Lithium CMS 4.04c and earlier versions that fundamentally compromises the application's security boundaries. This weakness exists in the classes/index.php file where user-supplied input is improperly validated and processed, creating an avenue for remote attackers to manipulate file inclusion mechanisms. The vulnerability specifically manifests when the siteconf[curl] parameter contains directory traversal sequences such as .. (dot dot) characters, which allows attackers to navigate beyond the intended directory structure and access arbitrary local files on the server. The attack vector is particularly insidious because it leverages legitimate file inclusion functionality while exploiting the lack of proper input sanitization, enabling attackers to execute arbitrary PHP code within the context of the web application.
The technical exploitation of this vulnerability follows a precise sequence that demonstrates the dangerous interplay between user input and server-side file processing. Attackers can craft malicious POST requests to news/comment.php containing PHP code that gets stored in the db/comments/news/ directory structure. When classes/index.php processes this data, it fails to properly validate the siteconf[curl] parameter, allowing the directory traversal sequence to resolve to files outside the intended scope. This flaw directly maps to CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. The vulnerability enables attackers to include and execute local files that may contain malicious code, effectively bypassing normal access controls and potentially leading to complete system compromise.
The operational impact of this vulnerability extends far beyond simple data exposure, as it provides attackers with the capability to execute arbitrary code on the target server with the privileges of the web application. This remote code execution vulnerability creates a persistent threat vector that can be exploited to establish backdoors, exfiltrate sensitive data, or use the compromised server as a launch point for further attacks within the network infrastructure. The implications are particularly severe because the vulnerability affects the core CMS functionality, potentially allowing attackers to modify or delete critical application files, access database credentials, or gain unauthorized administrative access to the content management system. Organizations running affected versions of Lithium CMS face significant risk of data breaches, service disruption, and potential regulatory compliance violations due to this unpatched vulnerability.
Mitigation strategies for this vulnerability must address both the immediate security gap and prevent similar issues in future development cycles. The most critical remediation involves implementing strict input validation and sanitization for all user-supplied parameters that are used in file inclusion operations, specifically ensuring that directory traversal sequences are rejected or properly encoded. Organizations should apply the vendor-provided security patches immediately and consider implementing additional protective measures such as web application firewalls that can detect and block suspicious directory traversal patterns. The implementation of principle of least privilege access controls, proper file permission settings, and regular security audits can further reduce the attack surface and potential impact of similar vulnerabilities. Additionally, developers should adopt secure coding practices that prevent user input from influencing file system operations, including the use of allowlists for valid file paths and proper input encoding techniques that neutralize potentially malicious sequences. This vulnerability serves as a stark reminder of the importance of input validation and secure file handling practices in web application development, aligning with ATT&CK technique T1059.007 for execution through PHP and T1566 for initial access through web applications.