12TB Steam breach leaks Portal 2 betas, Persona 6, Kingdom Hearts 4

Steam suffered two major data breaches in September 2026: achievement lists for unreleased games including Persona 6 and Kingdom Hearts 4 were exposed, and a 12-terabyte archive of game files from 2003–2013 leaked, containing Portal 2 beta builds and canceled project data. Outdated systems and misconfigured APIs were blamed.

• Achievement leak spoiled Persona 6 and Kingdom Hearts 4 details
• 12TB archive covers game files from 2003 to 2013
• Leaked data includes Portal 2 betas and canceled projects
• Cause cited as outdated systems and misconfigured APIs