Stranger joined temple instance without permission?

I was running my temple and got a whisper for a trade- this person proceeded to invite me to their party (I did not accept the invite) and then join my instance. I only noticed they were in because they said "I won't loot your stuff" and then we proceeded to wipe, with a chat message that we were both slain. The instance then crashed.


Is this possible? Is this an exploit that allows strangers to join temple instances with just a sent but not accepted party invite?