Are you sure this is a result of exploiting/cheating?
I have been experiencing it pretty regularly on my server ever since the Last Stand Update, which was the same time I updated to SM 1.10. It happens with various players playing as jockey/survivor, and it has happened to me while I am playing jockey, or survivor, and I know I am not cheating/exploiting.
The best explanation I can come up with so far, and this is something Marttt mentioned, is that it may be the result of the Anti Bhopping plugin https://github.com/SirPlease/L4D2-Co...4d2_nobhaps.sp
in combination with a setting on my server.
I have the cvar z_jockey_control_variance set to 0.45 instead of the default 0.7, which makes it so the survivor has less control over the jockey, and as such moves faster when jockeyed.
This is just a theory, but I think the anti-bhopping plugin is picking that up as bhopping and attempting to teleport the player, but since they are jockeyed, it gets all screwed up and teleports them outside of the map.
Hoping someone with more knowledge can give some insight on whether my theory makes any sense with the code in this anti-bhop plugin.
EDIT: Looking at that plugin again, the way the TeleportEntity function is used:
TeleportEntity(client, NULL_VECTOR, NULL_VECTOR, CurVelVec);
Should only change their velocity and not actually teleport them to a new location, so now I am questioning my theory.