A security breach at HBO earlier this week appears to have led to a new episode of the "Game of Thrones" TV series leaking online on Friday, August 4.

Hackers reportedly obtained 1.5 terabytes of stolen data from HBO’s servers in a recent breach, but they only initially published script outlines on the web. Episode 4 of season 7 has now leaked online in a low-quality format.

This episode appears to be genuine, but it’s not clear if it’s the final edited cut. The copy has a “for internal viewing only” watermark attached, The Verge says.

HBO has had to battle with Game of Thrones leaks a number of times in the past. The first four episodes of season 5 leaked online, thanks to advanced screeners that are sent out to members of the press. An HBO subsidiary also released a season 6 episode a day early. HBO decided to scrap screeners for season 7, but it appears this is the first time an episode has leaked due to a security breach at the network.