Format string vulnerability in the Epic Games Unreal engine client, as used in multiple games, allows remote servers to execute arbitrary code via (1) the CLASS parameter in a DLMGR command, (2) a malformed package (PKG), and possibly (3) the LEVEL parameter in a WELCOME command.
https://exchange.xforce.ibmcloud.com/vulnerabilities/45090
https://exchange.xforce.ibmcloud.com/vulnerabilities/45089
https://exchange.xforce.ibmcloud.com/vulnerabilities/45088
http://www.securityfocus.com/archive/1/496297/100/0/threaded