A poisoned VS Code extension breached GitHub — 3,800 internal repos stolen

GitHub has confirmed that a malicious Visual Studio Code extension compromised one of its employees' machines, leading to an unauthorized access of internal code repositories. The attacker claims to have packaged and stolen roughly 3,800 GitHub internal repos, and the company admits the claim aligns with its investigation so far.

The offending plugin was a poisoned version of the popular Nx Console extension (version 18.95.0), briefly available on the Microsoft Visual Studio Code marketplace on May 18. The attacker stole a contributor's token to gain publishing rights, then pushed a malicious update that included credential-stealing code.

Although the Nx team detected and removed the rogue version within 11 minutes, a GitHub employee had already downloaded it. The malicious payload silently exfiltrated Git credentials, VS Code extension storage, AWS keys, and 1Password vault data from the host. With those credentials, the attacker bypassed perimeter defenses and directly downloaded a large cache of GitHub's private repositories.

GitHub says it detected and contained the device intrusion on May 19. The security team urgently rotated all critical keys overnight, prioritizing high-value credentials. The company continues to analyze logs and monitor for further activity, with a full report expected after the investigation concludes.