The @onescience/onecode npm package's postinstall hook runs a function that downloads a tarball from a hardcoded bare IPv4 address over HTTPS with TLS verification disabled (rejectUnauthorized: false). The tarball is extracted and an executable is installed and invoked. No hash or signature verification is performed on the downloaded artifact. The download source is not a publisher-owned domain but a bare IP on a non-standard port, enabling arbitrary code execution if the remote host or network is compromised. The package name and launcher mimic an unrelated project 'opencode', using environment variables and asset directories referencing 'opencode' while retrieving payloads from an unrelated IP endpoint. This behavior constitutes a supply chain malicious package threat.

Any user installing affected versions of @onescience/onecode will execute arbitrary code controlled by the attacker hosting the payload. This can lead to full compromise of the installer's environment. The lack of TLS certificate verification and absence of artifact integrity checks allow man-in-the-middle or remote host compromise to inject malicious payloads. The threat affects all users of the specified versions of the package.

No official patch or remediation is currently documented. Users should avoid installing the affected versions of @onescience/onecode listed. Verify package authenticity before installation and consider using package integrity verification tools. Monitor for updates from the package publisher or npm advisories for official fixes. Since no patch information is available, patch status is not yet confirmed — check the vendor advisory for current remediation guidance.