Bold Page Builder < 3.1.6 - PHP Object Injection

The bt_bb_get_grid AJAX action of the Bold Page Builder WordPress plugin before 3.1.6 passes user input into the unserialize() function without any validation or sanitisation, which could lead to a PHP Object Injection. Even though the plugin did not contain a suitable gadget to fully exploit the issue, other installed plugins on the blog could allow such issue to be exploited and lead to RCE in some cases.