CVE-2016-15025: generator-hottowel Cross-site Scripting vulnerability

The vulnerability stems from missing middleware handlers for asset paths (/js/, /images/, /styles/*) in app/templates/src/server/_app.js. In the vulnerable version, requests to these paths fell through to Express.js' default 404 handler, which reflected unsanitized user input in error responses. The application's own four0four.send404 handler (which mitigates XSS) was not invoked for these routes. While the root cause is the absence of specific middleware functions, no existing functions in the application code were directly vulnerable with high confidence - the vulnerability manifested due to the lack of proper routing configuration rather than flawed code in existing functions.