SNI: reset to default server if requested host was not found. Not only this is consistent with a case without SNI, but this also prevents abusing configurations that assume that the $host variable is limited to one of the configured names for a server. An example of potentially unsafe configuration: server { listen 443 ssl default_server; ... } server { listen 443; server_name example.com; location / { proxy_pass http://$host; } } Note: it is possible to negotiate "example.com" by SNI, and to request arbitrary host name that does not exist in the configuration above.

--- a/src/http/ngx_http_request.c
+++ b/src/http/ngx_http_request.c
@@ -1869,6 +1869,17 @@ ngx_http_set_virtual_server(ngx_http_req
         return NGX_ERROR;
     }
 
+#ifdef SSL_CTRL_SET_TLSEXT_HOSTNAME
+
+    if (hc->ssl_servername) {
+        if (rc == NGX_DECLINED) {
+            cscf = hc->addr_conf->default_server;
+            rc = NGX_OK;
+        }
+    }
+
+#endif
+
     if (rc == NGX_DECLINED) {
         return NGX_OK;
     }