GitHub confirmed on May 20, 2026 that attackers exfiltrated thousands of its internal source-code repositories after a company employee installed a poisoned Visual Studio Code extension. The Microsoft-owned platform said the cybercrime group TeamPCP's claim of roughly 3,800 stolen repositories was "directionally consistent" with its own investigation.
How the breach happened
GitHub's investigation traced the intrusion to a malicious VS Code extension installed on an employee's machine. The company said it removed the malicious extension version, isolated the endpoint and began incident response immediately, rotating critical secrets overnight with the highest-impact credentials prioritized first. GitHub added that it currently has no evidence that customer information stored outside its internal repositories was affected, while cautioning that the investigation is ongoing.
A 2.2 million-install extension
On May 21, GitHub confirmed the extension was Nx Console, a developer tool with more than 2.2 million installs. A backdoored version was published on the marketplace on May 18 and pulled after roughly 11 minutes, but that window was enough given how many machines auto-update. Security researcher Charlie Eriksen of Aikido Security warned that VS Code extensions have full access to everything on a developer's machine, including credentials, cloud keys and SSH keys, and noted that blocking a malicious component depends on it being identified first.
TeamPCP's ongoing campaign
TeamPCP, also tracked as UNC6780, specializes in supply-chain attacks against open-source security utilities and AI middleware. The group has previously compromised tools including Aqua's Trivy scanner, Checkmarx KICS, the LiteLLM library and TanStack, often using its self-replicating "Mini Shai-Hulud" worm to steal CI/CD credentials and publish infected package versions. Investigators traced both the GitHub intrusion and a parallel breach at Grafana Labs back to the earlier TanStack supply-chain compromise. TeamPCP is reportedly offering the stolen repositories for sale and has threatened to leak them if no buyer emerges.
A widening software supply-chain threat
The incident underscores how interpreted artifacts such as editor extensions and open-source packages have become a fast-moving attack surface that traditional endpoint security struggles to cover. It follows a string of recent enforcement and disruption actions, including the first global takedown of a VPN cybercrime service and Microsoft's move to disrupt the Fox Tempest malware-signing operation. Security teams advise developers who installed the affected extension to rotate GitHub tokens, npm tokens, cloud keys and other stored credentials without delay.
Reporting based on coverage from Help Net Security and GitHub.