Joomla! Core is prone to multiple vulnerabilities, including arbitrary file upload and information disclosure vulnerabilities. An attacker may leverage these issues to upload arbitrary code and run it in the context of the webserver process, which may facilitate unauthorized access or privilege escalation, or to obtain sensitive information that may help in launching further attacks. Joomla! Core versions 3.x.x ranging from 3.0.0 and up to and including 3.6.4 are vulnerable.
Update to Joomla! Core version 3.6.5 or latest