Cactus do not damage players or other entities beyond a specific coordinate.
above x- 1,048,575 no damage from north and south face of cactus
above z- 1,048,575 no damage from east and west face of cactus
negative cords are also effected at same number.
Replicated on multi player and single player.
Confirmed. This issue has an interesting cause: the hitbox of a cactus is smaller than the hitbox of a normal block. However, above the specified coords, the hitbox suddenly becomes a full block. This makes it impossible for the player to touch it. A better title would be: "Cacti have a wrong hitbox over x/z +/- 1,048,575".