diff --git a/packages/webpack/src/config/server.js b/packages/webpack/src/config/server.js
index 9f8b9f876e..d921c43304 100644
--- a/packages/webpack/src/config/server.js
+++ b/packages/webpack/src/config/server.js
@@ -7,6 +7,11 @@ import VueSSRServerPlugin from '../plugins/vue/server'
 
 import WebpackBaseConfig from './base'
 
+const nativeFileExtensions = [
+  '.json',
+  '.js'
+]
+
 export default class WebpackServerConfig extends WebpackBaseConfig {
   constructor (...args) {
     super(...args)
@@ -20,11 +25,23 @@ export default class WebpackServerConfig extends WebpackBaseConfig {
 
   get externalsWhitelist () {
     return [
-      /\.(?!js(x|on)?$)/i,
+      this.isNonNativeImport.bind(this),
       ...this.normalizeTranspile()
     ]
   }
 
+  /**
+   * files *not* ending on js|json should be processed by webpack
+   *
+   * this might generate false-positives for imports like
+   * - "someFile.umd" (actually requiring someFile.umd.js)
+   * - "some.folder" (some.folder being a directory containing a package.json)
+   */
+  isNonNativeImport (modulePath) {
+    const extname = path.extname(modulePath)
+    return extname !== '' && !nativeFileExtensions.includes(extname)
+  }
+
   env () {
     return Object.assign(
       super.env(),