OpenTTD -- Denial of service (server/client) via invalid read

The OpenTTD Team reports:

When a client disconnects, without sending the “quit” or
“client error” message, the server has a chance of reading and
writing a just freed piece of memory. The writing can only
happen while the server is sending the map. Depending on what
happens directly after freeing the memory there is a chance of
segmentation fault, and thus a denial of service.