The npm package css-overscroll-contain versions 1.0.0 through 1.0.3 contains malicious code that executes immediately upon module load. This code performs host reconnaissance, steals credentials and sensitive environment variables, probes container escape techniques, and exfiltrates data to a hardcoded attacker endpoint. The package masquerades as a CSS utility but is incompatible with legitimate functionality. Any system with this package installed should be considered fully compromised.