The npm package @carvana.authentication-flows/shared version 19.2.1 is a malicious package that executes a preinstall script upon installation. This script collects host system information and user identity details, then exfiltrates this data to an attacker-controlled server. The package impersonates the Carvana organization by using a deceptive npm scope name, but contains no legitimate functionality. Its sole purpose is reconnaissance and data exfiltration during installation.