An issue was discovered in Joomla! 3.0.0 through 3.9.22. Improper filter blacklist configuration leads to a SQL injection vulnerability in the backend user list.
In Joomla! before 3.9.19, lack of input validation in the heading tag option of the "Articles - Newsflash" and "Articles - Categories" modules allows XSS.
An issue was discovered in Joomla! before 3.9.17. Incorrect ACL checks in the access level section of com_users allow the unauthorized deletion of usergroups.