Description
Joomla! Core is prone to multiple vulnerabilities, including cross-site scripting and PHP object injection vulnerabilities. Exploiting these issues could allow an attacker to execute arbitrary script code in the browser of an unsuspecting user in the context of the affected site, allowing the attacker to steal cookie-based authentication credentials and launch other attacks, or to possibly execute arbitrary PHP code within the context of the affected webserver process. Joomla! Core versions ranging from 2.5.0 and up to and including 3.9.2 are vulnerable.
Remediation
Update to Joomla! Core version 3.9.3 or latest