GitHub Announces Massive Leak of Companies' Internal Repository Data. Employee Devices Compromised via VS Code Extension

GitHub announced on May 20, 2026, at 1:04 p.m. (U.S. Pacific Time), via its official X account, an incident in which a large volume of companies' internal private repositories was leaked to third parties. The attack originated from the compromise of developer machines via a group of popular Visual Studio Code (VS Code) extensions, and it has been pointed out that the damage could extend to hundreds of companies across North America, Europe, and Japan. Coinciding with the full-scale arrival of the Claude Mythos era, the world's executives have once again been confronted with the fundamental risk of continuing to entrust source code—a company's lifeline—to external clouds.