(CNN) - There's a claim of a Facebook privacy breach within the Zuckerberg family.
It's from co-founder Mark Zuckerberg's oldest sister, Randi Zuckerberg, the former head of marketing for Facebook. She says she posted a family photo for friends on Facebook.
But a woman she doesn't know saw it and tweeted it to her nearly 40,000 Twitter followers.
Randi lashed out on the woman on Twitter saying it was only meant for her Facebook friends.
The woman apologized, saying she thought the photo was public because it was in her Facebook newsfeed.
It turns out the woman saw the photo because she's friends with another Zuckerberg sister who is tagged in the photo.
In a Tweet, Randi Zuckerberg later wrote the problem was not about privacy settings, but about human decency. She wrote it's good digital etiquette to ask permission before posting a friend's photo publicly.