[WebUI] relax CSRF defense. Closes #6882.

Allow HTTP request which has neither Origin nor Referer header included

src/webui/abstractwebapplication.cpp

@@ -392,9 +392,9 @@ bool AbstractWebApplication::isCrossSiteRequest(const Http::Request &request) co
     const QString refererValue = request.headers.value(Http::HEADER_REFERER);
 
     if (originValue.isEmpty() && refererValue.isEmpty()) {
-        if ((request.path == QLatin1String("/")) || (request.path == QLatin1String("/favicon.ico")))
+        // owasp.org recommends to block this request, but doing so will inevitably lead Web API users to spoof headers
-            return false;  // normal request
+        // so lets be permissive here
-        return true;
+        return false;
     }
 
     // sent with CORS requests, as well as with POST requests