verb to subscribe or unsubscribe to a specific event.
Other verb have validation for afb_req_value function value parsing, but those verb don't have validation.
Therefore, the strcasecmp function (afm-mediaplayer-binding.c:724, 740, 762, 766) will refer to NULL if the parameter is not sent on the corresponding verb request or if a other key sent, resulting in a Segmentation Fault.