vm2: NodeVM `require.external` without an explicit `require.root` grants unrestricted host filesystem access and full RCE

## Summary `NodeVM`'s `require.external` option lets sandboxed code `require()` local files and npm packages. When `require.external` is enabled and `require.root` is **not explicitly set to a path that excludes `node_modules`**, two defaults combine to fully defeat the sandbox: - `require.root` defaults to **unrestricted** — "if omitted every path is allowed." - `require.context` defaults to **`"host"`** — files loaded this way run through the **real Node.js `require()`**, not inside any vm2 sandbox. Sandboxed code can therefore `require()` a relative or absolute path to vm2's own installed package (`node_modules/vm2`), obtain the real, unwrapped `NodeVM`/`VM` classes, construct a brand-new **unrestricted** nested `NodeVM` instance, and execute arbitrary host OS commands via `child_process`. This is exploitable using **vm2's own documented "Quick Examples" configuration** in `README.md`: ```js const vm = new NodeVM({ require: { external: true, root: './', }, }); ``` `root: './'` reads as a safety restriction but, in any ordinary npm project layout, `./node_modules/vm2` sits inside that same directory tree — so the restriction does not exclude vm2 itself. An application built by following the README's quick-start guide is affected by default. ## Affected Versions All vm2 versions where `lib/resolver-compat.js`'s `makeResolverFromLegacyOptions` predates this report — confirmed present as of the current `main` (post-3.11.5, including all fixes through GHSA-8hg8-63c5-gwmx / Cate