CVE-2005-3020 in vBulletin
Summary
by MITRE
Multiple cross-site scripting (XSS) vulnerabilities in vBulletin before 3.0.9 allow remote attackers to inject arbitrary web script or HTML via the (1) group parameter to css.php, (2) redirect parameter to index.php, (3) email parameter to user.php, (4) goto parameter to language.php, (5) orderby parameter to modlog.php, and the (6) hex, (7) rgb, or (8) expandset parameter to template.php.
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Analysis
by VulDB Data Team • 12/24/2025
The vulnerability described in CVE-2005-3020 represents a critical cross-site scripting weakness affecting vBulletin versions prior to 3.0.9, fundamentally compromising web application security through multiple attack vectors. This vulnerability falls under the CWE-79 category of Cross-Site Scripting, specifically targeting the improper handling of user-supplied input within web applications. The flaw exists in the core application logic where parameters from HTTP requests are directly incorporated into dynamic web content without adequate sanitization or encoding mechanisms, creating persistent entry points for malicious actors to execute unauthorized scripts within victim browsers.
The technical exploitation occurs through eight distinct parameters across different PHP scripts within the vBulletin framework, each representing a separate injection point that could be leveraged by attackers. The group parameter in css.php, redirect parameter in index.php, email parameter in user.php, goto parameter in language.php, orderby parameter in modlog.php, and the hex, rgb, or expandset parameters in template.php all demonstrate a common pattern of insufficient input validation and output encoding. These parameters typically receive user-provided data that should be treated as potentially malicious, yet the application fails to properly sanitize or escape this data before incorporating it into web responses.
The operational impact of this vulnerability extends far beyond simple script execution, as it enables attackers to perform session hijacking, deface web pages, steal sensitive user information, and potentially escalate privileges within the application. When an attacker successfully injects malicious scripts through any of these parameters, they can manipulate user sessions, redirect victims to malicious sites, or extract cookies and authentication tokens that would otherwise remain secure. The vulnerability's widespread nature across multiple scripts within the application architecture means that a single exploitation attempt could provide access to various functional areas, making it particularly dangerous for organizations relying on vBulletin for community forums or user management systems.
Mitigation strategies for this vulnerability require immediate implementation of input validation and output encoding measures across all affected parameters. Organizations should apply the official vBulletin 3.0.9 patch or upgrade to a supported version that addresses these XSS vulnerabilities. The recommended security controls include implementing strict parameter validation using allowlists, applying proper HTML encoding to all user-supplied data before rendering in web responses, and implementing Content Security Policy headers to limit script execution. Additionally, security teams should conduct comprehensive code reviews focusing on parameter handling, implement web application firewalls to detect suspicious input patterns, and establish monitoring procedures to identify potential exploitation attempts. This vulnerability aligns with ATT&CK technique T1566 for initial access through malicious content and T1059 for command and control through script injection, emphasizing the need for layered defensive measures to protect against both immediate exploitation and potential lateral movement within compromised systems.