[SA21645] MyBB Avatar / Attachment Script Insertion Vulnerability

TITLE:
MyBB Avatar / Attachment Script Insertion Vulnerability

SECUNIA ADVISORY ID:
SA21645

VERIFY ADVISORY:
http://secunia.com/advisories/21645/

CRITICAL:
Less critical

IMPACT:
Cross Site Scripting

WHERE:
>From remote

SOFTWARE:
MyBB (formerly MyBulletinBoard) 1.x
http://secunia.com/product/4479/

DESCRIPTION:
Redworm has discovered a vulnerability in MyBB, which can be
exploited by malicious people to conduct script insertion attacks.

Input passed in uploaded attachments and avatars isn't properly
verified 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 when a specially crafted image is viewed directly
in the Microsoft Internet Explorer browser.

The vulnerability has been confirmed in version 1.1.7. Other versions
may also be affected.

SOLUTION:
Edit the source code to ensure that only valid image files with a
valid corresponding file extension can be uploaded.

PROVIDED AND/OR DISCOVERED BY:
Redworm

About:
This Advisory was delivered by Secunia as a free service to help
everybody keeping their systems up to date against the latest
vulnerabilities.

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http://secunia.com/about_secunia_advisories/

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