This weekend, the same email landed in the inboxes of an untold number of entertainment journalists. “1.5 TB of HBO data just leaked!!!” screamed the subject header, while the email itself, addressed "to all mankind," promised “the greatest leak of space era” and a link to a site that hosts an unreleased Game of Thrones script and not-yet-aired episodes of Ballers, Insecure, Room 104, and Barry. According to the hackers, there’s plenty more where that came from.

HBO has confirmed that an attack happened, though not the scope. “There has been a cyber incident directed at the company which has resulted in some stolen proprietary information, including some of our programming,” wrote HBO chairman and CEO Richard Plepler in an email to employees.

With streaming hacks like this one, though, it remains to be seen if size correlates with impact.

The Hack

On Sunday morning, an email from an unnamed group—though they appear to have adopted the tagline “HBO is falling”—went out to reporters, telling them, “You are lucky to be the first pioneers to witness and download the leak. Enjoy it & spread the words.” In addition to the link mentioned above, the email also included contact information for HBO communications VP Jeff Cusson.

Details of the hack itself are scarce, and HBO declined to comment on what it deemed an ongoing investigation. But unlike other recent high-profile Hollywood hacks, which relied on lax third-party security systems, the HBO hackers claim to have compromised HBO itself.

“We successfully penetrated HBO’s huge network and gathered most imporatnt [sic] files and films & scripts and so on,” one of the hackers wrote in an email to WIRED, promising both full episodes of Game of Thrones and upcoming feature films (presumably HBO originals). The hacker, identified in the email as “Mr. Smith,” also claimed to have “obtained alot [sic] about HBO’s staff and internal stuff.”

None of this has been verified, and hackers frequently overstate their claims. If true, though, this may ultimately resemble the Sony hack of 2014 more than Netflix’s recent Orange Is the New Black leak—which would be especially troubling for HBO.

Who’s Affected?

Well, HBO for starters. The casts, crews, and creators of the various series that ended up online. And any fans desperate enough to get a sneak peek at Ballers that they would download a file from a hacker-hosted website (or, likely soon enough, torrent it).

In truth, the answer to this question depends enough on the next question that we’ll get right into it.

How Serious Is This?

The leaking of unreleased shows has proven in the past to be, well, not that serious. It’s not ideal! But as pirated content continues to fall out of favor—BitTorrent traffic is about a fifth of what it was in 2011, according to network-equipment company Sandvine—the impact of shows leaking in the murkier depths of the internet has proven muted.

HBO knows that as well as anyone; in 2015, nearly half of Game of Thrones’ season five landed online ahead of its television debut. Even so, that season’s premiere set a record at the time for viewership, with an audience just shy of 8 million. Similarly, there’s no reason to expect that obscure online availability will do much to crimp either Insecure or Ballers.

The eventual scope could differentiate this leak, though. As the Sony hack demonstrated, internal emails can do serious financial and reputational damage, both to a company in general and individuals within it. Airing dirty laundry has a higher ceiling for harm than airing Room 104.

The hackers don’t appear to have asked for money (although what conversations they may have had, if any, with HBO prior to the release are unknown), which implies that, short of law enforcement action, there may not be a way to prevent future leaks. In which case the most important remaining question may not be how much data is left to leak but what kind.

Additional reporting by Andy Greenberg.