Improper client input validation for FreeRDP gateway connections allows to overwrite memory

FreeRDP is a free implementation of the Remote Desktop Protocol (RDP), released under the Apache license. All FreeRDP clients prior to version 2.4.1 using gateway connections (`/gt:rpc`) fail to validate input data. A malicious gateway might allow client memory to be written out of bounds. This issue has been resolved in version 2.4.1. If you are unable to update then use `/gt:http` rather than /gt:rdp connections if possible or use a direct connection without a gateway.