Leakage of unnecessary information frequently does not present any kind of significant defectin an application's security. Even highly verbose stack traces and other debugging messages may sometimes provide you with little leverage in seeking to attack the application.
In other cases, however, you may discover sources of information that are of great value in developing your attack. For example, you may find lists of user-names, the precise versions of software components, or the internal structure and functionality of the server-side application logic.
Because of this possibility, any serious assault on an application should include a forensic examination of both the application itself and publicly available resources so that you can gather any information that may be of use in formulating your attacks against it. On some occasions, information gathered in this way can provide the foundation for a complete compromise of the application that disclosed it.