> “The good news is that in Signal the attack is very difficult to execute,” Green noted. “The reason is that in order to add someone to your group, I need to know the group ID. Since the group ID is a random 128-bit number (and is never revealed to non-group-members or even the server) that pretty much blocks the attack. The main exception to this is former group members, who already know the group ID — and can now add themselves back to the group with impunity.”

Sounds like making a mountain out of a molehill.