Description
MyBB (aka MyBulletinBoard) 1.4.2 does not properly handle an uploaded file with a nonstandard file type that contains HTML sequences, which allows remote attackers to cause that file to be processed as HTML by Internet Explorer's content inspection, aka "Incomplete protection against MIME-sniffing." NOTE: this could be leveraged for XSS and other attacks.
Remediation
References
Related Vulnerabilities
Drupal Permissions, Privileges, and Access Controls Vulnerability (CVE-2012-4554)
PHP Improper Input Validation Vulnerability (CVE-2017-7189)
WordPress Plugin FG PrestaShop to WooCommerce Cross-Site Scripting (3.19.1)
Moodle Improper Access Control Vulnerability (CVE-2016-8643)
WordPress Plugin Spreadsheet (wpSS) Cross-Site Scripting (0.62)