CVE-2005-0511 in vBulletin
Summary
by MITRE
misc.php for vBulletin 3.0.6 and earlier, when "Add Template Name in HTML Comments" is enabled, allows remote attackers to execute arbitrary PHP code via nested variables in the template parameter.
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Analysis
by VulDB Data Team • 12/24/2025
The vulnerability identified as CVE-2005-0511 represents a critical remote code execution flaw in vBulletin versions 3.0.6 and earlier, specifically within the misc.php script. This issue arises from improper input validation and sanitization when the "Add Template Name in HTML Comments" feature is enabled, creating a pathway for malicious actors to inject and execute arbitrary PHP code on affected systems. The vulnerability stems from the application's failure to properly escape or validate template parameters before processing them, allowing attackers to manipulate the template parsing mechanism through nested variable injection techniques. This flaw demonstrates a classic insecure direct object reference vulnerability combined with code injection, where user-controllable input directly influences the execution flow of the application's template engine.
The technical exploitation of this vulnerability occurs when an attacker crafts malicious template parameters containing nested variables that, when processed by the vulnerable vBulletin installation, get interpreted as executable PHP code. The vulnerability is particularly dangerous because it leverages the legitimate template processing functionality of the application to execute arbitrary code with the privileges of the web server. When the "Add Template Name in HTML Comments" setting is enabled, the application includes template names within HTML comments, but fails to properly sanitize the template parameter values. This creates an environment where nested variable syntax can be manipulated to bypass normal input validation mechanisms and execute code directly within the PHP interpreter. The vulnerability aligns with CWE-94, which describes "Improper Control of Generation of Code ('Code Injection')" and represents a specific instance of command injection within template processing contexts.
The operational impact of CVE-2005-0511 is severe and far-reaching for organizations running vulnerable vBulletin installations, as it provides attackers with complete system compromise capabilities. Successful exploitation allows remote attackers to execute arbitrary commands on the web server, potentially leading to data breaches, system takeover, and further network infiltration. Attackers can leverage this vulnerability to establish persistent backdoors, exfiltrate sensitive data, or use the compromised server as a launching point for attacks against other systems within the network perimeter. The vulnerability's remote nature means that exploitation can occur without requiring any prior authentication or local access, making it particularly attractive to threat actors. Organizations may face significant regulatory and compliance implications, as this vulnerability could result in unauthorized access to protected data and potential violations of data protection regulations.
Mitigation strategies for CVE-2005-0511 should prioritize immediate patching of affected vBulletin installations to version 3.0.7 or later, which contains the necessary security fixes for this vulnerability. System administrators should disable the "Add Template Name in HTML Comments" feature if it is not essential for operations, as this setting directly enables the exploitation vector. Additionally, implementing web application firewalls and input validation measures can provide additional layers of protection against similar attacks. Organizations should conduct thorough security assessments of their vBulletin installations to identify and remediate any other potential vulnerabilities within the application. Network segmentation and access controls should be implemented to limit the potential impact of successful exploitation attempts. The vulnerability also highlights the importance of maintaining up-to-date security practices and following secure coding guidelines to prevent similar issues in future software development cycles. This vulnerability serves as a historical example of how template injection flaws can lead to complete system compromise and underscores the critical importance of proper input validation and sanitization in web applications.