The Cactus Will affect owners, but will not affect non-owners
Linked issues
is duplicated by 6
MCPE-813
Cactus does not damage multiplayer guests.
Resolved
MCPE-1897
Clients not taking damage from cacti
Resolved
MCPE-2102
When in multiplayer, people that join your server do not take damage from cacti
Resolved
MCPE-2185
2nd player dont take cactus damage
Resolved
MCPE-2354
Cactus glitch
Resolved
1 more links
Does this still affect 0.5.0?
edit – apparently it does.