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
PHP Improper Input Validation Vulnerability (CVE-2013-4248)
WordPress Plugin MDC Private Message Cross-Site Scripting (1.0.0)
Oracle JRE Exposure of Sensitive Information to an Unauthorized Actor Vulnerability (CVE-2026-22016)
TYPO3 Insertion of Sensitive Information into Log File Vulnerability (CVE-2021-32767)