CVE-2001-0475 in vBulletin
Summary
by MITRE
index.php in Jelsoft vBulletin does not properly initialize a PHP variable that is used to store template information, which allows remote attackers to execute arbitrary PHP code via special characters in the templatecache parameter.
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Analysis
by VulDB Data Team • 10/06/2025
The vulnerability identified as CVE-2001-0475 affects Jelsoft vBulletin software versions prior to 3.0.1, representing a critical security flaw that exploits improper variable initialization in the index.php script. This issue stems from a fundamental failure in the application's input validation mechanisms where the templatecache parameter is not adequately sanitized or initialized before being processed. The flaw exists within the software's template handling system, specifically in how it manages template information storage and retrieval. When attackers manipulate the templatecache parameter with specially crafted special characters, the uninitialized PHP variable becomes susceptible to exploitation, creating a pathway for arbitrary code execution on the affected server. This vulnerability falls under the category of improper initialization of variables, which is classified as CWE-457 in the Common Weakness Enumeration catalog, and represents a classic example of a buffer over-read or variable misuse vulnerability.
The operational impact of this vulnerability is severe as it allows remote attackers to execute arbitrary PHP code on the target system without requiring authentication or prior access. Attackers can leverage this flaw to inject malicious code that may result in complete system compromise, data exfiltration, or the deployment of backdoors. The vulnerability specifically targets the template caching mechanism, which is a core component of the bulletin board system's functionality. When the application processes the templatecache parameter, the uninitialized variable can be manipulated to overwrite memory locations or inject executable code directly into the PHP runtime environment. This type of vulnerability is particularly dangerous because it can be exploited through simple HTTP requests, making it accessible to attackers with basic web exploitation knowledge. The attack vector aligns with ATT&CK technique T1059.007 for command and scripting interpreter, specifically PHP, where adversaries leverage application vulnerabilities to execute malicious code remotely.
Mitigation strategies for CVE-2001-0475 require immediate patching of the affected Jelsoft vBulletin software to version 3.0.1 or later, which contains the necessary fixes for proper variable initialization. Organizations should implement input validation measures to sanitize all template parameters before processing, ensuring that special characters are properly escaped or filtered. Network administrators should deploy web application firewalls to monitor and block suspicious templatecache parameter values that contain potentially dangerous character sequences. Additionally, implementing proper code review processes and static analysis tools can help identify similar variable initialization issues in other parts of the application codebase. Security teams should also consider restricting access to the affected application through network segmentation and implementing robust logging mechanisms to detect exploitation attempts. The vulnerability demonstrates the importance of proper variable initialization practices in PHP applications and serves as a reminder of the critical need for comprehensive input validation in web applications. Organizations should conduct thorough vulnerability assessments to identify other potential instances of uninitialized variables or similar flaws in their code repositories, as this type of vulnerability can lead to remote code execution and complete system compromise when exploited by malicious actors.