An unreleased episode of Game of Thrones has been published online ahead of its TV debut on Sunday. Episode 4 of season 7 has now leaked online in a low-quality format — thanks to Google Drive postings in a Reddit thread. The Verge can confirm this episode is genuine, and the copy includes a “for internal viewing only” watermark attached.

HBO was subject to a security breach earlier this week, allowing hackers to reportedly obtain 1.5 terabytes of stolen data from the company’s US servers. Sources familiar with HBO’s security leak tell The Verge that this was not related to this episode leak. This latest episode has leaked from a distribution partner and not as a direct result of the recent HBO security breach. Hackers have so far only published published script outlines on the web, rather than full episodes.

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 advance screeners that are sent out to members of the press. A HBO subsidiary also released a season 6 episode a day early. HBO decided to scrap screeners for season 7, but that hasn’t stopped an episode leaking from a distribution partner. The Verge has reached out to HBO for comment, and we’ll update you accordingly.

Update, 9:50AM ET: Article updated with additional details on a leak from a distribution partner.