The web application uses the HTTP GET method to process a request and includes sensitive information in the query string of that request.
When sensitive information is sent, use the POST method (e.g. registration form).
At a minimum, attackers can garner information from query strings that can be utilized in escalating their method of attack, such as information about the internal workings of the application or database column names. Successful exploitation of query string parameter vulnerabilities could lead to an attacker impersonating a legitimate user, obtaining proprietary data, or simply executing actions not intended by the application developers. Examples of sensitive information may include secrets such as session identifiers, passwords, access tokens, or API keys; Personally Identifiable Information (PII) such as email addresses or phone numbers; records or logs of private activities; communications that are expected to be private; etc. Successful exploitation of query string parameter vulnerabilities could lead to an attacker impersonating a legitimate user, obtaining proprietary data, or simply executing actions not intended by the application developers.
Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)