Concrete5 through 8.5.5 deserializes Untrusted Data. The vulnerable code is located within the controllers/single_page/dashboard/system/environment/logging.php Logging::update_logging() method. User input passed through the logFile request parameter is not properly sanitized before being used in a call to the file_exists() PHP function. This can be exploited by malicious users to inject arbitrary PHP objects into the application scope (PHP Object Injection via phar:// stream wrapper), allowing them to carry out a variety of attacks, such as executing arbitrary PHP code.
Concrete CMS (formerly concrete5) before 8.5.5 allows remote authenticated users to conduct XSS attacks via a crafted survey block. This requires at least Editor privileges.
The Express Entries Dashboard in Concrete5 8.5.4 allows stored XSS via the name field of a new data object at an index.php/dashboard/express/entries/view/ URI.