FreeRDP is a free implementation of the Remote Desktop Protocol (RDP), released under the Apache license. In affected versions a malicious server might trigger out of bound writes in a connected client. Connections using GDI or SurfaceCommands to send graphics updates to the client might send 0 width/height or out of bound rectangles to trigger out of bound writes.

With 0 width or heigth the memory allocation will be 0 but the missing bounds checks allow writing to the pointer at this (not allocated) region. This issue has been patched in FreeRDP 2.4.1.