OpenSSF/OSV advisory MAL-2026-6294 confirms this npm version as malicious. The package's postinstall.js script runs automatically on `npm install` and collects host identifying data (os.hostname()) along with process environment variables (process.env), then transmits the data over HTTPS. This shape — system-information harvesting at install time and outbound network transmission via the `https` module — is a classic install-time exfiltration pattern...
Source
OpenSSF Malicious Packages via OSV
Summary
Malicious code in cue-mcp (npm)
Details
The package's postinstall.js script runs automatically on `npm install` and collects host identifying data (os.hostname()) along with process environment variables (process.env), then transmits the data over HTTPS. This shape — system-information harvesting at install time and outbound network transmission via the `https` module — is a classic install-time exfiltration pattern. There is no legitimate purpose served by reading the installer's environment variables and hostname during postinstall for a package of this kind. Environment variables on developer and CI machines routinely contain credentials (NPM_TOKEN, GITHUB_TOKEN, AWS keys, CI secrets), so this beacon constitutes credential exfiltration risk against any system that installs the package.
Decision reason
OpenSSF Malicious Packages via OSV confirms cue-mcp@9999.99.99 as malicious (MAL-2026-6294): Malicious code in cue-mcp (npm)