ganking exploit

[Ynir]

Yumyum is a lvl 70 blood elf warlock on Tichondrius, a PvP server.

She is used to being ganked here, there & everywhere, it is part of the contract. But there is ganking activity at flight points in contested areas that seems illegal, and unavoidable.

The moment she dismounts at the flight point she is attacked and killed by the guard npcs, although she has done nothing to provoke anyone. There is always an alliance nearby when this happens. It is not apparent to me how the deed is done.

A crude example of this activity involves a rogue who saps a victim and vanishes, leaving the victim to be netted and killed by the guards. This is not an exploit.

Another example is the enemy warlock standing at the flight point with his voidwalker. Voidy attacks the victim, and the guards are misdirected to kill the victim. This is exploitation of a bug, and was supposed to have been fixed in a recent patch.

The attacks I'm asking about don't involve a pet, or an invisible attacker, as far as I can tell. How is this accomplished, and what can be done to defend?