A Task can have permissions applied. Similar to Events, you will be able to choose the options of who and how they can access the Task. 

Set permissions when creating a new Task - Firstly create a new task, open the task and hit edit to update the permissions. All access levels available are below:

• All Group Members - you can grant permissions to all Group Members.

• Assignees - Keep as assignees only if you'd like this to be only accessible to people who have been assigned to the task.