The Doomsday engine versions less than or equal to 1.8.6 and 1.9.0 suffer from a format string bug in Con_Message and Con_Printf.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/45317/Doomsday-engine.txt
Source: https://packetstormsecurity.com/files/45317/Doomsday-engine.txt.html