CVE-2006-1717 in MyBB
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in newthread.php in MyBB (aka MyBulletinBoard) 1.10, when configured to permit new threads by unregistered users, allows remote attackers to inject arbitrary web script or HTML via the username.
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Analysis
by VulDB Data Team • 04/30/2019
The vulnerability identified as CVE-2006-1717 represents a critical cross-site scripting flaw within MyBB version 1.10, specifically affecting systems configured to allow unregistered users to create new threads. This security weakness resides in the newthread.php script which processes user submissions without adequate input validation mechanisms. The flaw manifests when the application fails to properly sanitize user-provided username data, creating an avenue for malicious actors to inject arbitrary web scripts or HTML content directly into the application's output streams. The vulnerability is particularly concerning because it targets the registration process for new threads, which occurs when users submit content without authentication, making it accessible to anyone with web browser access.
The technical implementation of this XSS vulnerability stems from insufficient sanitization of the username parameter within the newthread.php script. When unregistered users submit thread creation requests, the application accepts the username input and displays it without proper encoding or filtering of potentially malicious content. This allows attackers to embed script tags, javascript code, or other HTML elements that execute in the context of other users' browsers when they view the affected thread. The vulnerability operates under CWE-79 which specifically addresses Cross-Site Scripting flaws, where the application fails to properly validate or encode user-controllable data before incorporating it into dynamically generated web pages. The attack vector is particularly dangerous as it leverages the application's legitimate functionality to deliver malicious payloads to unsuspecting users.
The operational impact of this vulnerability extends beyond simple script injection, as it enables attackers to perform various malicious activities including session hijacking, credential theft, defacement of forum content, and redirection to malicious websites. When legitimate users browse threads containing malicious username content, their browsers execute the embedded scripts, potentially compromising their sessions and exposing sensitive information. The vulnerability affects the core forum functionality and can be exploited to manipulate the entire user experience, making it a significant threat to forum administrators and community members alike. From an ATT&CK perspective, this vulnerability aligns with T1059.007 which covers Scripting and T1531 which addresses Account Access Removal, as the attack can lead to unauthorized access and manipulation of user sessions. The flaw particularly impacts organizations using MyBB for community forums, discussion platforms, or collaborative environments where user-generated content is a primary feature.
Mitigation strategies for CVE-2006-1717 require immediate implementation of input validation and output encoding measures within the MyBB application. Administrators should ensure that all user-provided data, particularly username fields, undergo rigorous sanitization before being displayed in forum threads. The recommended approach involves implementing proper HTML encoding for all dynamic content and employing Content Security Policy headers to prevent execution of unauthorized scripts. System administrators should also consider updating to patched versions of MyBB that address this vulnerability, as version 1.10 was superseded by releases containing proper input validation mechanisms. Additionally, implementing proper access controls and user authentication mechanisms can reduce the attack surface, though this represents a secondary mitigation since the vulnerability specifically targets unregistered users. Network-level protections such as web application firewalls can provide additional defense-in-depth measures, though they should not be relied upon as the sole solution for this type of vulnerability.