The rushstack-lockfile-explorer npm package version 1.2.3 contains malicious code that installs a dependency from a custom domain which executes an information stealer during installation. This malware targets sensitive tokens related to npm, git, and CI/CD environments. Any system with this package installed should be considered fully compromised, and all secrets and keys stored on that system must be rotated immediately from a different, trusted computer. Removing the package alone does not guarantee removal of all malicious components.