Gadu-Gadu does not properly perform protocol handling, which allows remote attackers to conduct cross-site request forgery (CSRF) attacks and add arbitrary user accounts or cause a denial of service as administrators via an unspecified "crafted link," possibly related to the gg protocol.
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.