GitHub confirms internal repository theft as TeamPCP claims attack

GitHub disclosed that it is investigating unauthorized access to its internal repositories after attackers compromised an employee's device through a malicious Visual Studio Code extension.

The company says there is currently no evidence that customer repositories or enterprise data were affected, though the incident appears to have exposed thousands of private internal repositories.

GitHub’s initial alert, published early on May 20, confirmed an investigation into unauthorized access to internal repositories and stated that it had not found evidence of impact on customer data stored outside the company’s infrastructure.

We are investigating unauthorized access to GitHub’s internal repositories. While we currently have no evidence of impact to customer information stored outside of GitHub’s internal repositories (such as our customers’ enterprises, organizations, and repositories), we are closely…

— GitHub (@github) May 19, 2026

A few hours later, the company provided additional details, revealing that the intrusion originated from a “poisoned VS Code extension” installed on an employee's device.

According to GitHub, the compromised endpoint was isolated immediately after detection, and the malicious extension version was removed. The company also said it initiated incident response procedures right away and began rotating sensitive credentials, prioritizing high-impact secrets overnight to reduce the risk of further compromise.

“Our current assessment is that the activity involved exfiltration of GitHub-internal repositories only,” the company said in a follow-up statement. GitHub added that the attackers’ claims of obtaining roughly 3,800 repositories were “directionally consistent” with the company’s ongoing investigation.

1/ We are sharing additional details regarding our investigation into unauthorized access to GitHub's internal repositories.

Yesterday we detected and contained a compromise of an employee device involving a poisoned VS Code extension. We removed the malicious extension version,…

— GitHub (@github) May 20, 2026

GitHub is one of the world’s largest software development platforms, hosting source code repositories and collaboration tools used by millions of developers and enterprises globally. The platform forms a critical part of the software supply chain, meaning security incidents affecting its infrastructure can have broad implications for developers, businesses, and open-source projects.

Treat actor “TeamPCP” claimed responsibility for the breach on the cybercrime forum Breached. In a post advertising the allegedly stolen data, the hackers claimed to possess source code and internal organizational data tied to GitHub’s main platform.

“There is a total of around ~4,000 repos of private code here,” the actor wrote, while offering to provide samples to prospective buyers. The threat group also claimed it was seeking offers above $50,000 and threatened to leak the data publicly if no buyer emerged.

The attackers published a link allegedly containing a list of compromised repositories, though GitHub has not publicly confirmed the authenticity of any leaked samples or repository listings beyond acknowledging that the attackers’ repository count broadly aligns with internal findings.

TeamPCP has previously been linked to several high-profile intrusions targeting software supply chain and cloud infrastructure. The group was associated with breaches affecting vulnerability scanning firm Trivy, AI gateway project LiteLLM, and systems tied to the European Commission.

GitHub said it is continuing to analyze logs, validate secret rotation efforts, and monitor for follow-on malicious activity. The company added that it will publish a more comprehensive incident report after the investigation is completed.