JasperServer in JasperReports Server Community Project 3.7.0 and 3.7.1 uses a predictable _flowExecutionKey parameter, which makes it easier for remote attackers to conduct cross-site request forgery (CSRF) attacks via a brute-force approach.
Cross-Site Request Forgery The web application does not, or cannot, sufficiently verify whether a request was intentionally provided by the user who sent the request, which could have originated from an unauthorized actor.