CVE-2003-0295 in vBulletin
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in private.php for vBulletin 3.0.0 Beta 2 allows remote attackers to inject arbitrary web script and HTML via the "Preview Message" capability.
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Analysis
by VulDB Data Team • 01/20/2025
The vulnerability identified as CVE-2003-0295 represents a critical cross-site scripting flaw within the vBulletin 3.0.0 Beta 2 forum software, specifically affecting the private.php script. This vulnerability resides in the "Preview Message" functionality which enables users to preview their private messages before sending them. The flaw allows remote attackers to inject malicious web script and HTML content directly into the message preview mechanism, creating a persistent vector for malicious code execution within the victim's browser context. This represents a classic XSS vulnerability that undermines the fundamental security assumptions of web applications by permitting unauthorized code injection.
The technical implementation of this vulnerability stems from insufficient input validation and output sanitization within the private message preview feature. When users submit private messages for preview, the application fails to properly sanitize or escape user-supplied input before rendering it in the HTML output context. This allows attackers to embed malicious script tags or other HTML elements that execute when the preview is displayed to other users. The vulnerability specifically targets the preview functionality rather than the actual message delivery mechanism, making it particularly insidious as it can be exploited during the message composition phase. According to CWE standards, this maps directly to CWE-79 which describes improper neutralization of input during web page generation, specifically in the context of cross-site scripting attacks. The vulnerability aligns with ATT&CK technique T1566.001 which covers the exploitation of web application vulnerabilities through malicious input injection.
The operational impact of this vulnerability extends beyond simple script execution as it provides attackers with the capability to perform various malicious activities within the targeted user's browser session. Attackers could potentially steal session cookies, redirect users to malicious websites, deface forum content, or harvest sensitive information from authenticated users. The preview functionality makes this attack vector particularly dangerous as it does not require the victim to be actively engaged in sending messages, but rather simply viewing the preview page. The vulnerability affects all users of the affected vBulletin version, making it a widespread concern for forum administrators and users alike. The attack can be executed without authentication requirements, as the preview mechanism is accessible to all users, and the malicious code executes in the context of the victim's browser session, potentially compromising their entire session and access privileges.
Mitigation strategies for this vulnerability should focus on immediate input sanitization and output encoding within the preview functionality. The most effective remediation involves implementing proper HTML entity encoding for all user-supplied content before rendering it in the preview context. This approach ensures that any potentially malicious script tags or HTML elements are rendered as harmless text rather than executable code. Additionally, administrators should implement Content Security Policy headers to further restrict script execution and prevent unauthorized code injection. The vulnerability highlights the critical importance of input validation and output encoding practices, particularly in web applications where user-generated content is displayed. Regular security updates and patches should be implemented immediately upon availability, as this vulnerability represents a known flaw in the specific vBulletin version mentioned. The fix should also include comprehensive testing of all preview mechanisms within the application to ensure no similar vulnerabilities exist in other components. Organizations should also consider implementing web application firewalls and intrusion detection systems to monitor for exploitation attempts and provide additional layers of defense against such attacks.