The remote host is vulnerable to multiple attack vectors
The version of MyBB installed on the remote host is vulnerable to an html-injection flaw. An attacker, exploiting this flaw, would be able to execute script code within the browser of an unsuspecting user. Allegedly, the host is also vulnerable to several unspecified vulnerabilities. While the details are sketchy, the vendor has addressed the issue.
Upgrade to MyBB 1.4.6 or later.