In FreeRDP less than or equal to 2.0.0, there is an out-of-bounds read in rfx_process_message_tileset. Invalid data fed to RFX decoder results in garbage on screen (as colors). This has been patched in 2.1.0.
To mitigate this flaw, do not use /rfx, /gfx or /network:auto command line options in the freerdp client.