1. A computer-implemented method for security testing of web applications with specialized payloads, the method comprising: submitting a test to a web application, wherein the test comprises a payload with a set of constraints; receiving a response from the web application; deriving one or more constraints from the response; updating the set of constraints of the payload with the derived one or more constraints; synthesizing, by a computer processor, the payload for the updated set of constraints; and iterating the test having the synthesized payload with the updated set of constraints.