An issue was discovered in templates/beez3/html/com_content/article/default.php in Joomla! before 3.6.5. Inadequate permissions checks in the Beez3 layout override of the com_content article view allow users to view articles that should not be publicly accessible, as demonstrated by an index.php?option=com_content&view=article&id=1&template=beez3 request.
https://www.joomla.org/announcements/release-news/5693-joomla-3-6-5-released.html