The yandex-geobase npm package versions 2.1.0, 2.1.2, 2.2.0, 2.9.0, and 3.9.0 contain malicious code that executes a postinstall script. This script sends an HTTP GET request to a hardcoded bare IP address on a non-standard port, leaking package and environment information to an external host. The package is described as a dependency confusion test placeholder, but its behavior can compromise build environments and potentially the host system. Removal of the package is recommended, but full system compromise is possible, requiring secret and key rotation.