The young British actress shared a series of personal pictures from a recent visit to Japan with her friends and family on the social networking site, including topless images of Maisie posing on a rock, with her back to the camera.
The shots were never intended to be viewed by the general public, but this week (begs05Dec16), they surfaced on Reddit.com, sending her fans into a spin.
Her representative has since confirmed the photos are real and were lifted from her Facebook profile, but made it clear there was nothing controversial about the snaps themselves.
"The images online were shared from Maisie's personal social media account," her spokesperson told the New York Post's Page Six column. "The images are not explicit in nature, but pictures of Maisie and close friends at a spa at a recent visit in Japan."
The 19-year-old, who is known for her role as Arya Stark on the hit fantasy drama series, spent time in Japan last week (ends02Dec16), when she campaigned against popular marine shows in a bid to stop the culture of hunting dolphins across the nation.
Maisie is an ambassador for Ric O'Barry's Dolphin Project, which is dedicated to the welfare and protection of dolphins around the world.
"These animals travel the ocean," she explained during a visit to the town of Taiji, where Flipper trainer-turned-marine activist Ric O'Barry filmed his Academy Award-winning 2009 documentary The Cove. "That's what they explore daily. No tank will be big enough. No tank will ever be deep enough, ever be exciting enough."