Casting Frost Shock with Hailstorm active causes Frost Shock to hit targets it should not, including critters, neutral enemies and other players. This bug has been active for at very least three months.
It is easy to reproduce, just have the Hailstorm talent, gain stacks, cast Frost Shock on an enemy, if there is a PvP flagged player nearby, even if you are not flagged, you will hit the player and flag yourself, or engage a neutral enemy.