Robocode through 1.9.3.5 allows remote attackers to cause external service interaction (DNS), as demonstrated by a query for a unique subdomain name within an attacker-controlled DNS zone, because of a .openStream call within java.net.URL.
Robocode before 1.6.0 allows user-assisted remote attackers to "access the internals of the Robocode game" via unspecified vectors related to the AWT Event Queue.