FlagThis

Abstract

On 11 May 2026, the threat actor group TeamPCP compromised 42 TanStack npm packages by chaining three GitHub Actions vulnerabilities to hijack the project's legitimate CI/CD pipeline. The attackers then published 84 malicious package versions carrying valid SLSA Build Level 3 provenance attestations, making them indistinguishable from legitimate releases by standard verification methods. The payload, a variant of TeamPCP's Mini Shai-Hulud credential-stealing worm, propagated autonomously by using harvested npm tokens to infect additional packages, ultimately reaching over 170 packages and 400 malicious versions across npm and PyPI within five hours.