Steam leak that exposed a decade of game history wasn’t even a hack
Fans witness unseen footage of games that Valve killed off.
Steam logo is seen displayed on a phone screen. By Jakub Porzycki/NurPhoto via Getty Images.
- A 12TB Valve data leak exposed internal builds and game assets from 2003 to 2013.
- The leak included early versions of Portal 2, Left 4 Dead, Sonic games, and Grand Theft Auto 5.
- A Valve-affiliated dataminer said the data came from public sources, not hacked internal servers.
- No game data after 2013 appears affected because Valve changed its storage system that year.
Key Takeaways by nexos.ai, reviewed by Cybernews staff.
Valve has suffered a data breach that leaked 12 terabytes of internal game data and abandoned projects spanning a decade. Is it the company’s fault?
The breach is said to have exposed internal builds and game assets from 2003 to 2013, including early versions of popular Valve titles like Portal 2 and Left 4 Dead.
The leak was announced by Gabe Follower, a Valve-affiliated content creator and Steam dataminer.
In the data dump, users also found a model of The Weaponizer from the canceled game Half-Life 2.
Follower dubs this “teraleak,” one of Valve’s biggest breaches of all time, after Steam servers appeared online.
“It’s important to note that we are talking about the entire Steam library, not just Valve projects,”said Steam dataminer Gabe Follower in a YouTube video on the leak.
“So most of the builds are related to random projects.”
Notably, people have found developer versions of Grand Theft Auto 5, early versions of The Binding of Isaac, and beta versions of the Sonic games.
Developers can use Valve to create games and later release them on the company’s companion distribution platform, Steam.
Other gaming studios, like Rockstar (GTA) and Sega (Sonic), can distribute PC versions of their games on Steam.
The breach is significant, not just because of the amount of data exposed, but also because Valve wasn’t hacked.
Instead, someone who was “knowledgeable enough simply found an endpoint” and from there they were able to “download all the data without owning the necessary games in their Steam library,” said Follower.
All data was obtained from public sources and wasn’t obtained by accessing the company’s internal servers without authorization.
It’s unclear as to how Follower found out about the leak, but it’s likely he was tipped off.
Cybernews has reached out to Follower for comment.
In 2013, Valve changed its content distribution and storage system, replacing the older content system Steam2 with SteamPipe.
This is why no game data beyond 2013 was leaked in the breach.
Considering that these games and assets are from between 2003 and 2013, they may not even launch, as they were developed to be compatible with older hardware and drivers.
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Data breach hit Valve customers earlier this month
Earlier this month, Valve warned its European Steam hardware customers that their delivery details were likely exposed in a cyberattack affecting its shipping partner, CEVA Logistics.
The compromised data included names, addresses, phone numbers, emails, and purchase information.
In 2025, a breach that allegedly contained 89 million records was published on a popular data leak forum.
Cybernews researchers investigated the data sample and confirmed it only contained phone numbers and one-time codes. No passwords, email addresses, or other details were exposed.
Steam gave little credence to this breach, as it affected only one-time codes valid for 15 minutes. Or, in other words, the supposed leak of tens of millions of Steam customer data was worthless.
