CVE-2008-3966 in MyBB
Summary
by MITRE
Multiple cross-site scripting (XSS) vulnerabilities in MyBB (aka MyBulletinBoard) before 1.4.1 allow remote attackers to inject arbitrary web script or HTML via (1) a certain referrer field in usercp2.php, (2) a certain location field in inc/functions_online.php, and certain (3) tsubject and (4) psubject fields in moderation.php.
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Analysis
by VulDB Data Team • 10/08/2018
The CVE-2008-3966 vulnerability represents a significant cross-site scripting flaw affecting MyBulletinBoard versions prior to 1.4.1, demonstrating the critical importance of input validation in web application security. This vulnerability manifests across multiple attack vectors within the MyBB platform, specifically targeting fields that handle user-provided data without adequate sanitization. The affected components include the referrer field in usercp2.php, the location field in inc/functions_online.php, and both tsubject and psubject fields in moderation.php, each representing distinct pathways for malicious code injection. These vulnerabilities fall under CWE-79 which specifically addresses cross-site scripting flaws, highlighting the fundamental weakness in how the application processes and renders user input. The attack surface is particularly concerning as these fields are commonly used in user profile management and moderation activities, making them prime targets for exploitation by threat actors seeking to compromise user sessions or execute malicious code within the context of the vulnerable application.
The operational impact of this vulnerability extends beyond simple data corruption, as it enables attackers to manipulate user sessions and potentially gain unauthorized access to sensitive information. When users visit pages containing maliciously injected scripts, their browsers execute the code within the context of the vulnerable MyBB installation, creating opportunities for session hijacking, credential theft, or redirection to malicious sites. The specific nature of the attack vectors suggests that the vulnerability exploits the application's failure to properly escape or validate user input before rendering it in HTML contexts. The referrer field in usercp2.php likely represents a scenario where external links are displayed without proper sanitization, while the location field in inc/functions_online.php indicates a broader issue with how user profile information is handled during online status display. The moderation.php fields present a particularly dangerous attack surface as they relate to administrative functions, potentially allowing attackers to inject malicious content into threads or posts that could affect all users viewing the content.
Security practitioners should recognize this vulnerability as a classic example of insufficient input validation and output encoding, aligning with ATT&CK technique T1566 which covers the exploitation of web application vulnerabilities through injection attacks. The remediation approach must focus on implementing comprehensive input sanitization across all user-facing fields, particularly those that are rendered in HTML contexts. Organizations should implement proper HTML escaping mechanisms for all dynamic content, ensuring that user-provided data cannot be interpreted as executable code. The vulnerability also highlights the importance of regular security updates and patch management, as MyBB 1.4.1 and subsequent versions addressed these specific XSS flaws through improved input validation. Security measures should include regular code reviews focusing on data flow from user inputs to output rendering, implementing Content Security Policy headers to mitigate the impact of potential XSS exploitation, and establishing proper input validation frameworks that can prevent similar vulnerabilities from emerging in future versions of the application.