i heard from someone that anyone who use claymore up do 10.5 need to update do 10.6 ,what's the cause

Have a look at the 1st post in this thread, he has a change log there and it will tell you what the changes are between 10.5 and 10.6.
ok i/ve read:
"Latest version is v10.6:
- fixed critical issue in remote management feature (attacker could crash miner even in read-only mode)."
its about -mport option yes? so if somebody didn't used that option, older versions are safe ? correct ?