CVE-2004-1824 in vBulletin
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in Jelsoft vBulletin before 3.0 allows remote attackers to inject arbitrary web script or HTML via the what parameter to memberlist.php.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 07/06/2025
The vulnerability identified as CVE-2004-1824 represents a classic cross-site scripting flaw within the Jelsoft vBulletin platform prior to version 3.0. This security weakness specifically manifests in the memberlist.php script where the what parameter fails to properly sanitize user input before rendering it within the web page context. The vulnerability falls under the CWE-79 category of Cross-Site Scripting, which is one of the most prevalent and well-documented web application security flaws in the industry. Attackers can exploit this weakness by crafting malicious scripts or HTML content and injecting them through the vulnerable parameter, thereby bypassing the normal security restrictions that separate web application code from user-supplied data.
The technical execution of this XSS attack occurs when an attacker manipulates the what parameter in the memberlist.php URL to include malicious payloads. When the vulnerable application processes this input without proper validation or encoding, the injected scripts become part of the page's HTML output and execute in the context of other users' browsers who visit the affected page. This creates a persistent threat where malicious code can steal session cookies, redirect users to phishing sites, or perform unauthorized actions on behalf of victims. The vulnerability specifically targets the memberlist.php script which is commonly used for displaying user directories and member information, making it a high-value target for attackers seeking to compromise user sessions or spread malicious content across the forum.
From an operational perspective, this vulnerability presents significant risks to forum administrators and their user communities. The attack vector allows remote exploitation without requiring any authentication, making it particularly dangerous as it can be leveraged by anyone with access to the affected website. The impact extends beyond simple data theft to include potential account takeover scenarios where attackers can hijack user sessions and gain unauthorized access to personal information, private messages, and forum privileges. This vulnerability aligns with ATT&CK technique T1531 which focuses on using vulnerabilities in web applications to gain access to user sessions and execute malicious code in the context of legitimate users. The widespread use of vBulletin forums at the time meant that successful exploitation could affect numerous websites simultaneously, amplifying the potential damage.
Organizations should implement comprehensive mitigation strategies to address this vulnerability including immediate patching to version 3.0 or later where the XSS protection mechanisms have been properly implemented. Input validation and output encoding should be enforced at all points where user-supplied data enters the application, particularly in parameters that are directly rendered in web pages. The implementation of Content Security Policy headers can provide additional defense-in-depth measures to prevent execution of unauthorized scripts even if the primary vulnerability is not fully mitigated. Regular security audits and web application firewalls should be deployed to monitor for similar vulnerabilities in other components of the web application stack. The vulnerability demonstrates the critical importance of proper input sanitization and the principle of least privilege in web application development, ensuring that all user-supplied data is properly validated before being incorporated into dynamic web content.