In general, to fix uncontrolled path usage, normalize the user input, resolve it relative to a known safe root directory, and then verify that the resulting path is contained within that root. If the normalized path escapes the root, reject the request. For this server, the safe root is effectively ${process.cwd()}/dist. We should use path.resolve to join this root with the requested path, then ensure the resolved path starts with the root directory. This prevents directory traversal and absolute path attacks.

The best fix here is: (1) introduce an import of Node’s path module; (2) compute const distRoot = path.join(process.cwd(), 'dist') once per request (or outside the handler if appropriate); (3) take Req.url?.substring(1) || '' as the requested path segment, resolve it with path.resolve(distRoot, requestedPath), and (4) check that the resolved path starts with distRoot + path.sep or equals distRoot. If not, return 403. Then use this sanitized resolvedPath for both Fs.existsSync and Fs.readFileSync. This preserves existing functionality (files are still only served if in FileName, from loopback, and if they exist) while adding robust path validation.

Concretely in builder/source/utils/http-server.ts:

• Add import * as Path from 'node:path' at the top.
• Inside the request handler, compute const distRoot = Path.join(process.cwd(), 'dist') and const requestPath = Req.url?.substring(1) || ''.
• Derive const resolvedPath = Path.resolve(distRoot, requestPath).
• Before the FileName.includes/loopback/exists checks that depend on the path, add a guard: if !resolvedPath.startsWith(distRoot + Path.sep) && resolvedPath !== distRoot, respond with 403 and return.
• Replace both occurrences of `${process.cwd()}/dist/${Req.url?.substring(1)}` with resolvedPath.

No additional helper methods are strictly necessary beyond the new Path import and local variables.

In general, the fix is to ensure that any path derived from user input is constrained to a safe root directory. That means: (1) normalize the combined path (root + user input) using path.resolve (and optionally fs.realpathSync), and (2) verify that the normalized path is still under the intended root (dist), rejecting the request otherwise. Additionally, avoid using the raw URL for filesystem access; use the validated/normalized path instead.

For this snippet, the best minimal fix without changing functionality is:

• Introduce a constant DIST_ROOT that holds the absolute path to the dist directory, computed via path.resolve(process.cwd(), 'dist').
• Import Node’s path module as import * as Path from 'node:path'.
• For each usage of `${process.cwd()}/dist/${Req.url?.substring(1)}`, compute a safe path:
  • Take the requested path segment Req.url?.substring(1) || ''.
  • Normalize it with Path.normalize.
  • Resolve it against DIST_ROOT with Path.resolve(DIST_ROOT, requestedPath).
  • Optionally (more robustly) pass that resolved path through Fs.realpathSync in a try/catch to handle missing files cleanly.
  • Check that the final resolved path starts with DIST_ROOT + Path.sep (or is exactly DIST_ROOT) to ensure it doesn’t escape the root. If it does, respond with 403 and return.
• Replace both Fs.existsSync(...) and Fs.readFileSync(...) to use this validated resolved path (safePath) instead of reconstructing the string each time.

Concretely, inside RunDebugServer:

• Define const DIST_ROOT = Path.resolve(process.cwd(), 'dist') near the top of the function.
• Inside the request handler, once you’ve passed the FileName.includes(...) and loopback checks, compute the safe path as described.
• Use that safe path for existsSync and readFileSync.
• If resolving or realpathSync throws or if the path check fails, respond with 403 (for traversal) or 503/404 as appropriate and return.

This keeps the existing behavior (only serving files in FileName, still returning 503 when the file is not built) while adding proper path safety.