Node.js permission model bypass via unchecked Unix Domain Socket connections (UDS)

Summary

A flaw in Node.js's permission model allows Unix Domain Socket (UDS) connections to bypass network restrictions when --permission is enabled. Even without --allow-net, attacker-controlled inputs (such as URLs or socketPath options) can connect to arbitrary local sockets via net, tls, or undici/fetch. This breaks the intended security boundary of the permission model and enables access to privileged local services, potentially leading to privilege escalation, data exposure, or local code execution.

• The issue affects users of the Node.js permission model on version v25.

In the moment of this vulnerability, network permissions (--allow-net) are still in the experimental phase.