Suppose I share a status update with a custom list with a few friends on it. Now if a friend that is on that custom list shares it publicly then will all our mutual friends (some of whom are not on the custom list) and the public in general be able to see my shared (by a friend) status update?
EDIT: I should also add that the default privacy setting for my updates is limited to friends only and only friends can see posts in my timeline.
If you're just writing text and posting the update to a limited group you'll be at the mercy of copy/paste functionality. The share link doesn't appear for text status updates
People that you've shared with on your friend's lists will only be able to see it, however, if your with friend has chosen to share posts they're tagged in with a wider audenience then you'll be at the mercy of that setting.
The share button also will not show up here, but you'll likely still be at the mercy of the copy/paste function.
If you share to a restricted list the share button will not appear and your friends will have to tell the story about where they got it from without you.
If you share an image to a restricted list the share will not appear and your friends will have to either post a link to the image or upload the image themselves after downloading it to repost it on their timeline.
Nothing you share with Facebook (even if it's set to only me) should be considered private. Bugs, settings, and future service updates could accidentally/intentionally display this information to your friends; so post with care.
