Two vulnerabilities have been reported in MyBB, which can be exploited by malicious users to conduct cross-site scripting and script insertion attacks.

1) Input passed to the avatar URL field in the user control panel is not properly sanitised before being used. This can be exploited to insert arbitrary HTML and script code, which will be executed in a user's browser session in the context of an affected site when the malicious data is viewed.

2) Uploaded images are not properly sanitised before being used. This can be exploited to execute arbitrary HTML and script code in a user's browser session in context of an affected site by tricking a user into downloading a previously uploaded malformed image file.

Successful exploitation of this vulnerability requires that the user cancels the download of the file once and that the user's browser is Internet Explorer 6.

The vulnerabilities are reported in version 1.4.5 and vulnerability #2 is also reported in 1.2.14. Other versions may also be affected.

Solution
Update to version 1.4.6.
Further details available in Customer Area

Provided and/or discovered by
Jacques Copeau

Changelog
Further details available in Customer Area

Original Advisory
http://blog.mybboard.net/2009/05/03/mybb-146-released-security-update/

1) http://archives.neohapsis.com/archives/fulldisclosure/2009-05/0018.html
2) http://archives.neohapsis.com/archives/fulldisclosure/2009-05/0256.html

Deep Links
Links available in Customer Area