CVE-2016-9406 in MyBB
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in the User control panel in MyBB (aka MyBulletinBoard) before 1.8.7 and MyBB Merge System before 1.8.7 might allow remote attackers to inject arbitrary web script or HTML via unspecified vectors.
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Analysis
by VulDB Data Team • 08/08/2020
The vulnerability identified as CVE-2016-9406 represents a cross-site scripting flaw within the User control panel of MyBB, a popular bulletin board software platform. This issue affects versions prior to 1.8.7 and also extends to the MyBB Merge System. The vulnerability stems from insufficient input validation and output encoding mechanisms that fail to properly sanitize user-supplied data before it is rendered in web pages. Attackers can exploit this weakness to inject malicious scripts or HTML content that executes in the context of other users' browsers when they view affected pages.
The technical nature of this vulnerability aligns with CWE-79, which defines Cross-Site Scripting as a weakness that occurs when an application includes untrusted data in a new web page without proper validation or escaping, allowing attackers to execute scripts in the victim's browser. The unspecified vectors mentioned in the description suggest that multiple entry points within the user control panel could be exploited, potentially including form fields, URL parameters, or other user input mechanisms. This broad attack surface increases the likelihood of successful exploitation and makes the vulnerability particularly concerning for administrators managing forums with numerous user interactions.
From an operational perspective, this vulnerability presents significant risks to forum administrators and their user communities. When exploited, the XSS attack could allow attackers to steal session cookies, redirect users to malicious websites, deface forum content, or perform actions on behalf of authenticated users. The impact extends beyond simple data theft as attackers could leverage this vulnerability to establish persistent access to the forum environment, potentially leading to complete compromise of user accounts and forum data integrity. The vulnerability affects the core user management functionality, making it particularly dangerous as it targets the most interactive and frequently used components of the platform.
Organizations and administrators should immediately implement mitigations including upgrading to MyBB version 1.8.7 or later, which contains the necessary patches to address the XSS vulnerability. Additional protective measures include implementing proper input validation at multiple layers, enforcing strict output encoding for all user-generated content, and deploying web application firewalls that can detect and block malicious script injection attempts. The ATT&CK framework categorizes this vulnerability under T1059.008 for Scripting, as it allows adversaries to execute malicious scripts within the victim environment. Administrators should also consider implementing content security policies to limit script execution and monitor for unusual user behavior that might indicate exploitation attempts. Regular security audits and vulnerability assessments should be conducted to ensure that similar issues do not persist in other components of the forum software or related systems.