Smarty Security stream restriction bypass through stream: resource

Smarty is a template engine for PHP, facilitating the separation of presentation (HTML/CSS) from application logic. From 5.0.0 until 5.8.4, Smarty's stream: resource-name handling does not adequately restrict which PHP stream wrappers and filter chains can be referenced from a template, allowing a php://filter-wrapped resource name to be used to read the contents of arbitrary local files accessible to the PHP process. An attacker able to author or influence a template's resource reference could exploit this to disclose sensitive file contents outside the intended template/config scope. This issue is fixed in version 5.8.4.