GitHub has confirmed that a breach of its internal repositories is directly linked to the TanStack npm supply-chain attack, demonstrating how a single compromised developer tool can cascade into a major security incident. The company stated that the intrusion began when an employee installed a malicious version of the Nx Console Visual Studio Code extension, which had been poisoned during the wider TanStack compromise. This attack chain allowed threat actors to gain initial access to GitHub’s internal infrastructure, ultimately exposing approximately 3,800 internal repositories to unauthorized access.
The original TanStack attack occurred on May 11, 2026, when the TeamPCP threat group compromised 42 npm packages and published 84 malicious versions in just six minutes. The attackers exploited a sophisticated combination of GitHub Actions vulnerabilities, including a “Pwn Request” attack using pull_request_target abuse, cache poisoning across fork-to-base trust boundaries, and OIDC token extraction from runner memory. This technique produced the first npm supply-chain attack with valid SLSA Build Level 3 attestations, making the malicious packages appear completely legitimate to security scanners and developers.
The malicious Nx Console extension version 18.95.0 was available on the Visual Studio Marketplace for approximately 18 minutes and on OpenVSX for another 36 minutes before being removed. Despite the short window, the poisoned extension deployed a payload designed to steal credentials and secrets from developer environments, targeting npm, AWS, Kubernetes, GitHub, GCP, and Docker platforms. The Nx development team confirmed that one of their developers was compromised through the TanStack supply-chain leak, which exposed GitHub credentials through the GitHub CLI, allowing attackers to run workflows on their repository as a contributor.
GitHub’s Chief Information Security Officer Alexis Wales confirmed that the company secured the compromised device and rotated critical secrets, prioritizing the highest-impact credentials first. While GitHub has not officially attributed the attack to a specific group, TeamPCP claimed access to GitHub source code and approximately 4,000 repositories of private code on the Breached forum, demanding at least $50,000 for the stolen data. The incident also affected other organizations, including UiPath, Guardrails AI, OpenSearch, and Grafana Labs, which confirmed its GitHub environment breach originated from the same TanStack attack.
This incident highlights the severe risks of modern software supply chains, where one compromised dependency can ripple across thousands of developers and organizations faster than security teams can respond. The attack demonstrates that even organizations with strong security practices, including two-factor authentication, remain vulnerable to sophisticated supply-chain attacks that exploit trust relationships between packages, build tools, and automated workflows. Developers and security teams must now prioritize hardening CI/CD pipelines,Token rotation, extension verification, and continuous monitoring of package updates as potential attack vectors.
This article has been indexed from CySecurity News – Latest Information Security and Hacking Incidents
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