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.
Use of Externally-Controlled Format String The product uses a function that accepts a format string as an argument, but the format string originates from an external source.