Joomla : Security Vulnerabilities, CVEs, (Bypass) CVSS score >= 9

An issue was discovered in Joomla! 2.5.0 through 3.10.6 & 4.0.0 through 4.1.0. A user row was not bound to a specific authentication mechanism which could under very special circumstances allow an account takeover.

In Joomla! before 3.8.2, a bug allowed third parties to bypass a user's 2-factor authentication method.

The file scanning mechanism of JFilterInput::isFileSafe() in Joomla! CMS before 3.6.5 does not consider alternative PHP file extensions when checking uploaded files for PHP content, which enables a user to upload and execute files with the `.php6`, `.php7`, `.phtml`, and `.phpt` extensions. Additionally, JHelperMedia::canUpload() did not blacklist these file extensions as uploadable file types.

Joomla! Core is prone to a vulnerability that lets attackers upload arbitrary files because the application fails to properly verify user-supplied input. An attacker can exploit this vulnerability to upload arbitrary code and run it in the context of the webserver process. This may facilitate unauthorized access or privilege escalation; other attacks are also possible. Joomla! Core versions 1.5.x ranging from 1.5.0 and up to and including 1.5.15 are vulnerable.