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.
https://lists.debian.org/debian-lts-announce/2023/10/msg00008.html
https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-5mr4-28w3-rc84
http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00080.html