Description
Joomla! Core is prone to a race condition, where a session which was expected to be destroyed would be recreated. Attackers can exploit this issue to perform unauthorized actions. Joomla! Core versions 3.x.x ranging from 3.0.0 and up to and including 3.8.7 are vulnerable.
Remediation
Update to Joomla! Core version 3.8.8 or latest