The vulnerability stems from JSDom's resource loading mechanism when configured with {resources: "usable"}. The stack trace in Tenable's example shows resource-queue.js and per-document-resource-loader.js are directly involved in processing file:// requests. These functions handle resource loading at the implementation level but lack granular access control to block local resources despite being in a security-sensitive context. The maintainers' own dispute confirms the explicit opt-in nature of this behavior, which matches the described vulnerability pattern of insufficient access control granularity.