Connect is a stack of middleware that is executed in order in each request.
The "methodOverride" middleware allows the http post to override the method of the request with the value of the "_method" post key or with the header "x-http-method-override".
Because the user post input was not checked, req.method could contain any kind of value. Because the req.method did not match any common method VERB, connect answered with a 404 page containing the "Cannot
[url]" content. The method was not properly encoded for output in the browser.
~ curl "localhost:3000" -d "_method=<script src=http://nodesecurity.io/xss.js></script>" Cannot <SCRIPT SRC=HTTP://NODESECURITY.IO/XSS.JS></SCRIPT> /
Update to the newest version of Connect or disable methodOverride. It is not possible to avoid the vulnerability if you have enabled this middleware in the top of your stack.