From 154b340fe31dc338fa17def69fa334db2501cb22 Mon Sep 17 00:00:00 2001
From: devjiwonchoi <devjiwonchoi@gmail.com>
Date: Tue, 7 Oct 2025 14:22:42 +0200
Subject: [PATCH 1/5] Skip internal routes in middleware

---
 crates/next-api/src/middleware.rs             | 35 ++++++++++--
 crates/next-core/src/next_config.rs           |  6 +++
 packages/next/src/build/entries.ts            |  3 +-
 packages/next/src/build/index.ts              |  6 +--
 packages/next/src/build/webpack-config.ts     |  1 +
 .../webpack/plugins/middleware-plugin.ts      | 54 +++++++++++++------
 packages/next/src/server/config-schema.ts     |  1 +
 packages/next/src/server/config-shared.ts     |  7 +++
 .../src/server/lib/router-utils/filesystem.ts |  3 +-
 .../lib/router-utils/setup-dev-bundler.ts     |  3 +-
 packages/next/src/server/next-server.ts       | 12 +++--
 .../utils/get-default-middleware-matcher.ts   | 21 ++++++++
 12 files changed, 118 insertions(+), 34 deletions(-)
 create mode 100644 packages/next/src/shared/lib/router/utils/get-default-middleware-matcher.ts

diff --git a/crates/next-api/src/middleware.rs b/crates/next-api/src/middleware.rs
index 63304b4b9d3f47..696512a4078bd8 100644
--- a/crates/next-api/src/middleware.rs
+++ b/crates/next-api/src/middleware.rs
@@ -42,6 +42,31 @@ use crate::{
     route::{Endpoint, EndpointOutput, EndpointOutputPaths},
 };
 
+/// Rust implementation of the TypeScript getDefaultMiddlewareMatcher function
+/// Generates default middleware matcher patterns that respect skipMiddlewareNextInternalRoutes
+fn get_default_middleware_matcher(
+    skip_middleware_next_internal_routes: Option<bool>,
+) -> MiddlewareMatcher {
+    let skip_internal = skip_middleware_next_internal_routes.unwrap_or(true);
+
+    if skip_internal {
+        // Skip "/_next/" internal routes, except for "/_next/data/" which is needed for
+        // client-side navigation. Do not consider basePath as the user cannot create a
+        // route starts with underscore.
+        MiddlewareMatcher {
+            regexp: Some(rcstr!("^(?!.*\\/\\_next\\/(?!data\\/)).*")),
+            original_source: rcstr!("/:path*"),
+            ..Default::default()
+        }
+    } else {
+        MiddlewareMatcher {
+            regexp: Some(rcstr!("^/.*$")),
+            original_source: rcstr!("/:path*"),
+            ..Default::default()
+        }
+    }
+}
+
 #[turbo_tasks::value]
 pub struct MiddlewareEndpoint {
     project: ResolvedVc<Project>,
@@ -165,6 +190,8 @@ impl MiddlewareEndpoint {
             .map(|i18n| i18n.locales.len() > 1)
             .unwrap_or(false);
         let base_path = next_config.base_path().await?;
+        let skip_middleware_next_internal_routes =
+            next_config.skip_middleware_next_internal_routes().await?;
 
         let matchers = if let Some(matchers) = config.middleware_matcher.as_ref() {
             matchers
@@ -216,11 +243,9 @@ impl MiddlewareEndpoint {
                 })
                 .collect()
         } else {
-            vec![MiddlewareMatcher {
-                regexp: Some(rcstr!("^/.*$")),
-                original_source: rcstr!("/:path*"),
-                ..Default::default()
-            }]
+            vec![get_default_middleware_matcher(
+                *skip_middleware_next_internal_routes,
+            )]
         };
 
         if matches!(runtime, NextRuntime::NodeJs) {
diff --git a/crates/next-core/src/next_config.rs b/crates/next-core/src/next_config.rs
index 29d625b90c097c..4d0b20600c8c6f 100644
--- a/crates/next-core/src/next_config.rs
+++ b/crates/next-core/src/next_config.rs
@@ -103,6 +103,7 @@ pub struct NextConfig {
     asset_prefix: Option<RcStr>,
     base_path: Option<RcStr>,
     skip_middleware_url_normalize: Option<bool>,
+    skip_middleware_next_internal_routes: Option<bool>,
     skip_trailing_slash_redirect: Option<bool>,
     i18n: Option<I18NConfig>,
     cross_origin: Option<CrossOriginConfig>,
@@ -1343,6 +1344,11 @@ impl NextConfig {
         Vc::cell(self.base_path.clone())
     }
 
+    #[turbo_tasks::function]
+    pub fn skip_middleware_next_internal_routes(&self) -> Vc<Option<bool>> {
+        Vc::cell(self.skip_middleware_next_internal_routes)
+    }
+
     #[turbo_tasks::function]
     pub fn cache_handler(&self, project_path: FileSystemPath) -> Result<Vc<OptionFileSystemPath>> {
         if let Some(handler) = &self.cache_handler {
diff --git a/packages/next/src/build/entries.ts b/packages/next/src/build/entries.ts
index ccd03f221f8cfd..2927325f0d88c8 100644
--- a/packages/next/src/build/entries.ts
+++ b/packages/next/src/build/entries.ts
@@ -45,6 +45,7 @@ import {
   isInstrumentationHookFilename,
 } from './utils'
 import { getPageStaticInfo } from './analysis/get-page-static-info'
+import { getDefaultMiddlewareMatcher } from '../shared/lib/router/utils/get-default-middleware-matcher'
 import { normalizePathSep } from '../shared/lib/page-path/normalize-path-sep'
 import { normalizePagePath } from '../shared/lib/page-path/normalize-page-path'
 import type { ServerRuntime } from '../types'
@@ -898,7 +899,7 @@ export async function createEntrypoints(
 
       if (isMiddlewareFile(page)) {
         middlewareMatchers = staticInfo.middleware?.matchers ?? [
-          { regexp: '.*', originalSource: '/:path*' },
+          getDefaultMiddlewareMatcher(params.config),
         ]
       }
 
diff --git a/packages/next/src/build/index.ts b/packages/next/src/build/index.ts
index fd059406d324ad..735b75db15fc59 100644
--- a/packages/next/src/build/index.ts
+++ b/packages/next/src/build/index.ts
@@ -150,6 +150,7 @@ import { isEdgeRuntime } from '../lib/is-edge-runtime'
 import { recursiveCopy } from '../lib/recursive-copy'
 import { lockfilePatchPromise, teardownTraceSubscriber } from './swc'
 import { getNamedRouteRegex } from '../shared/lib/router/utils/route-regex'
+import { getDefaultMiddlewareMatcher } from '../shared/lib/router/utils/get-default-middleware-matcher'
 import { getFilesInDir } from '../lib/get-files-in-dir'
 import { eventSwcPlugins } from '../telemetry/events/swc-plugins'
 import { normalizeAppPath } from '../shared/lib/router/utils/app-paths'
@@ -2590,10 +2591,7 @@ export default async function build(
           functionsConfigManifest.functions['/_middleware'] = {
             runtime: staticInfo.runtime,
             matchers: staticInfo.middleware?.matchers ?? [
-              {
-                regexp: '^.*$',
-                originalSource: '/:path*',
-              },
+              getDefaultMiddlewareMatcher(config),
             ],
           }
 
diff --git a/packages/next/src/build/webpack-config.ts b/packages/next/src/build/webpack-config.ts
index 04b97894050939..09e65bdc933bd8 100644
--- a/packages/next/src/build/webpack-config.ts
+++ b/packages/next/src/build/webpack-config.ts
@@ -2081,6 +2081,7 @@ export default async function getBaseWebpackConfig(
           dev,
           sriEnabled: !dev && !!config.experimental.sri?.algorithm,
           rewrites,
+          nextConfig: config,
           edgeEnvironments: {
             __NEXT_BUILD_ID: buildId,
             NEXT_SERVER_ACTIONS_ENCRYPTION_KEY: encryptionKey,
diff --git a/packages/next/src/build/webpack/plugins/middleware-plugin.ts b/packages/next/src/build/webpack/plugins/middleware-plugin.ts
index 3f36ac8b09026a..1d78740f0e0b9c 100644
--- a/packages/next/src/build/webpack/plugins/middleware-plugin.ts
+++ b/packages/next/src/build/webpack/plugins/middleware-plugin.ts
@@ -5,6 +5,7 @@ import type {
 import type { EdgeSSRMeta } from '../loaders/get-module-build-info'
 import type { MiddlewareMatcher } from '../../analysis/get-page-static-info'
 import { getNamedMiddlewareRegex } from '../../../shared/lib/router/utils/route-regex'
+import { getDefaultMiddlewareMatcher } from '../../../shared/lib/router/utils/get-default-middleware-matcher'
 import { getModuleBuildInfo } from '../loaders/get-module-build-info'
 import { getSortedRoutes } from '../../../shared/lib/router/utils'
 import { webpack, sources } from 'next/dist/compiled/webpack/webpack'
@@ -36,6 +37,7 @@ import type { CustomRoutes } from '../../../lib/load-custom-routes'
 import { isInterceptionRouteRewrite } from '../../../lib/generate-interception-routes-rewrites'
 import { getDynamicCodeEvaluationError } from './wellknown-errors-plugin/parse-dynamic-code-evaluation-error'
 import { getModuleReferencesInOrder } from '../utils'
+import type { NextConfigComplete } from '../../../server/config-shared'
 
 const KNOWN_SAFE_DYNAMIC_PACKAGES =
   require('../../../lib/known-edge-safe-packages.json') as string[]
@@ -195,21 +197,29 @@ function getCreateAssets(params: {
         continue
       }
 
-      const matcherSource = metadata.edgeSSR?.isAppDir
-        ? normalizeAppPath(page)
-        : page
-
-      const catchAll = !metadata.edgeSSR && !metadata.edgeApiFunction
-
-      const { namedRegex } = getNamedMiddlewareRegex(matcherSource, {
-        catchAll,
-      })
-      const matchers = metadata?.edgeMiddleware?.matchers ?? [
-        {
-          regexp: namedRegex,
-          originalSource: page === '/' && catchAll ? '/:path*' : matcherSource,
-        },
-      ]
+      let matchers: MiddlewareMatcher[]
+      if (metadata?.edgeMiddleware?.matchers) {
+        matchers = metadata.edgeMiddleware.matchers
+      } else {
+        // For middleware at root with no explicit matchers, use getDefaultMiddlewareMatcher
+        // which respects skipMiddlewareNextInternalRoutes config
+        const catchAll = !metadata.edgeSSR && !metadata.edgeApiFunction
+        if (page === '/' && catchAll) {
+          matchers = [getDefaultMiddlewareMatcher(opts.nextConfig)]
+        } else {
+          const matcherSource = metadata.edgeSSR?.isAppDir
+            ? normalizeAppPath(page)
+            : page
+          matchers = [
+            {
+              regexp: getNamedMiddlewareRegex(matcherSource, {
+                catchAll,
+              }).namedRegex,
+              originalSource: matcherSource,
+            },
+          ]
+        }
+      }
 
       const isEdgeFunction = !!(metadata.edgeApiFunction || metadata.edgeSSR)
       const edgeFunctionDefinition: EdgeFunctionDefinition = {
@@ -818,6 +828,7 @@ interface Options {
   sriEnabled: boolean
   rewrites: CustomRoutes['rewrites']
   edgeEnvironments: EdgeRuntimeEnvironments
+  nextConfig: NextConfigComplete
 }
 
 export default class MiddlewarePlugin {
@@ -825,12 +836,20 @@ export default class MiddlewarePlugin {
   private readonly sriEnabled: Options['sriEnabled']
   private readonly rewrites: Options['rewrites']
   private readonly edgeEnvironments: EdgeRuntimeEnvironments
-
-  constructor({ dev, sriEnabled, rewrites, edgeEnvironments }: Options) {
+  private readonly nextConfig: Options['nextConfig']
+
+  constructor({
+    dev,
+    sriEnabled,
+    rewrites,
+    edgeEnvironments,
+    nextConfig,
+  }: Options) {
     this.dev = dev
     this.sriEnabled = sriEnabled
     this.rewrites = rewrites
     this.edgeEnvironments = edgeEnvironments
+    this.nextConfig = nextConfig
   }
 
   public apply(compiler: webpack.Compiler) {
@@ -886,6 +905,7 @@ export default class MiddlewarePlugin {
             rewrites: this.rewrites,
             edgeEnvironments: this.edgeEnvironments,
             dev: this.dev,
+            nextConfig: this.nextConfig,
           },
         })
       )
diff --git a/packages/next/src/server/config-schema.ts b/packages/next/src/server/config-schema.ts
index 31ddf66d65a7c9..072a0c4abcd8c3 100644
--- a/packages/next/src/server/config-schema.ts
+++ b/packages/next/src/server/config-schema.ts
@@ -677,6 +677,7 @@ export const configSchema: zod.ZodType<NextConfig> = z.lazy(() =>
     serverExternalPackages: z.array(z.string()).optional(),
     serverRuntimeConfig: z.record(z.string(), z.any()).optional(),
     skipMiddlewareUrlNormalize: z.boolean().optional(),
+    skipMiddlewareNextInternalRoutes: z.boolean().optional(),
     skipTrailingSlashRedirect: z.boolean().optional(),
     staticPageGenerationTimeout: z.number().optional(),
     expireTime: z.number().optional(),
diff --git a/packages/next/src/server/config-shared.ts b/packages/next/src/server/config-shared.ts
index 5ec7cf193f2cac..644c7c93cd3e2e 100644
--- a/packages/next/src/server/config-shared.ts
+++ b/packages/next/src/server/config-shared.ts
@@ -1249,6 +1249,12 @@ export interface NextConfig {
 
   skipMiddlewareUrlNormalize?: boolean
 
+  /**
+   * Skip Next.js internals route `/_next` from middleware.
+   * @default true
+   */
+  skipMiddlewareNextInternalRoutes?: boolean
+
   skipTrailingSlashRedirect?: boolean
 
   modularizeImports?: Record<
@@ -1529,6 +1535,7 @@ export const defaultConfig = Object.freeze({
   },
   htmlLimitedBots: undefined,
   bundlePagesRouterDependencies: false,
+  skipMiddlewareNextInternalRoutes: true,
 } satisfies NextConfig)
 
 export async function normalizeConfig(phase: string, config: any) {
diff --git a/packages/next/src/server/lib/router-utils/filesystem.ts b/packages/next/src/server/lib/router-utils/filesystem.ts
index cd276cd69eb58b..be19679c7878f7 100644
--- a/packages/next/src/server/lib/router-utils/filesystem.ts
+++ b/packages/next/src/server/lib/router-utils/filesystem.ts
@@ -31,6 +31,7 @@ import { pathHasPrefix } from '../../../shared/lib/router/utils/path-has-prefix'
 import { normalizeLocalePath } from '../../../shared/lib/i18n/normalize-locale-path'
 import { removePathPrefix } from '../../../shared/lib/router/utils/remove-path-prefix'
 import { getMiddlewareRouteMatcher } from '../../../shared/lib/router/utils/middleware-route-matcher'
+import { getDefaultMiddlewareMatcher } from '../../../shared/lib/router/utils/get-default-middleware-matcher'
 import {
   APP_PATH_ROUTES_MANIFEST,
   BUILD_ID_FILE,
@@ -314,7 +315,7 @@ export async function setupFsCheck(opts: {
     } else if (functionsConfigManifest?.functions['/_middleware']) {
       middlewareMatcher = getMiddlewareRouteMatcher(
         functionsConfigManifest.functions['/_middleware'].matchers ?? [
-          { regexp: '.*', originalSource: '/:path*' },
+          getDefaultMiddlewareMatcher(opts.config),
         ]
       )
     }
diff --git a/packages/next/src/server/lib/router-utils/setup-dev-bundler.ts b/packages/next/src/server/lib/router-utils/setup-dev-bundler.ts
index 0df31c045d5a25..c66090d75a19d7 100644
--- a/packages/next/src/server/lib/router-utils/setup-dev-bundler.ts
+++ b/packages/next/src/server/lib/router-utils/setup-dev-bundler.ts
@@ -48,6 +48,7 @@ import {
 } from '../../../shared/lib/constants'
 
 import { getMiddlewareRouteMatcher } from '../../../shared/lib/router/utils/middleware-route-matcher'
+import { getDefaultMiddlewareMatcher } from '../../../shared/lib/router/utils/get-default-middleware-matcher'
 
 import {
   isMiddlewareFile,
@@ -472,7 +473,7 @@ async function startWatcher(
             serverFields.actualMiddlewareFile
           )
           middlewareMatchers = staticInfo.middleware?.matchers || [
-            { regexp: '^/.*$', originalSource: '/:path*' },
+            getDefaultMiddlewareMatcher(opts.nextConfig),
           ]
           continue
         }
diff --git a/packages/next/src/server/next-server.ts b/packages/next/src/server/next-server.ts
index 7e5f627ffb62ca..cdc8731129d2c2 100644
--- a/packages/next/src/server/next-server.ts
+++ b/packages/next/src/server/next-server.ts
@@ -71,6 +71,7 @@ import type { LoadComponentsReturnType } from './load-components'
 import isError, { getProperError } from '../lib/is-error'
 import { splitCookiesString, toNodeOutgoingHttpHeaders } from './web/utils'
 import { getMiddlewareRouteMatcher } from '../shared/lib/router/utils/middleware-route-matcher'
+import { getDefaultMiddlewareMatcher } from '../shared/lib/router/utils/get-default-middleware-matcher'
 import { loadEnvConfig } from '@next/env'
 import { urlQueryToSearchParams } from '../shared/lib/router/utils/querystring'
 import { removeTrailingSlash } from '../shared/lib/router/utils/remove-trailing-slash'
@@ -1455,13 +1456,13 @@ export default class NextNodeServer extends BaseServer<
       const middlewareModule = await this.loadNodeMiddleware()
 
       if (middlewareModule) {
+        const matchers = middlewareModule.config?.matchers || [
+          getDefaultMiddlewareMatcher(this.nextConfig),
+        ]
         return {
-          match: getMiddlewareRouteMatcher(
-            middlewareModule.config?.matchers || [
-              { regexp: '.*', originalSource: '/:path*' },
-            ]
-          ),
+          match: getMiddlewareRouteMatcher(matchers),
           page: '/',
+          matchers,
         }
       }
 
@@ -1471,6 +1472,7 @@ export default class NextNodeServer extends BaseServer<
     return {
       match: getMiddlewareMatcher(middleware),
       page: '/',
+      matchers: middleware.matchers,
     }
   }
 
diff --git a/packages/next/src/shared/lib/router/utils/get-default-middleware-matcher.ts b/packages/next/src/shared/lib/router/utils/get-default-middleware-matcher.ts
new file mode 100644
index 00000000000000..3d5c8830b0e27f
--- /dev/null
+++ b/packages/next/src/shared/lib/router/utils/get-default-middleware-matcher.ts
@@ -0,0 +1,21 @@
+import type { NextConfig } from '../../../../types'
+import type { MiddlewareMatcher } from '../../../../build/analysis/get-page-static-info'
+
+export function getDefaultMiddlewareMatcher({
+  skipMiddlewareNextInternalRoutes,
+}: NextConfig): MiddlewareMatcher {
+  if (skipMiddlewareNextInternalRoutes !== false) {
+    // Skip "/_next/" internal routes, except for "/_next/data/" which is needed for
+    // client-side navigation. Do not consider basePath as the user cannot create a
+    // route starts with underscore.
+    return {
+      regexp: '^(?!.*\\/\\_next\\/(?!data\\/)).*',
+      originalSource: '/((?!_next/(?!data/))[^]*)*',
+    }
+  }
+
+  return {
+    regexp: '^/.*$',
+    originalSource: '/:path*',
+  }
+}

From 1f7891dedae057930a2e33376b79f9019bdc76e0 Mon Sep 17 00:00:00 2001
From: devjiwonchoi <devjiwonchoi@gmail.com>
Date: Thu, 25 Sep 2025 16:44:38 +0200
Subject: [PATCH 2/5] Add test

---
 .../app/layout.tsx                             | 11 +++++++++++
 .../app/page.tsx                               |  3 +++
 ...skip-next-internal-routes-base-path.test.ts | 18 ++++++++++++++++++
 .../middleware.ts                              |  7 +++++++
 .../next.config.js                             |  6 ++++++
 .../app/layout.tsx                             | 11 +++++++++++
 .../app/page.tsx                               |  3 +++
 ...e-skip-next-internal-routes-opt-out.test.ts | 18 ++++++++++++++++++
 .../middleware.ts                              |  7 +++++++
 .../next.config.js                             |  6 ++++++
 .../app/layout.tsx                             | 11 +++++++++++
 .../app/page.tsx                               |  3 +++
 ...iddleware-skip-next-internal-routes.test.ts | 18 ++++++++++++++++++
 .../middleware.ts                              |  7 +++++++
 .../next.config.js                             |  4 ++++
 15 files changed, 133 insertions(+)
 create mode 100644 test/e2e/middleware-skip-next-internal-routes-base-path/app/layout.tsx
 create mode 100644 test/e2e/middleware-skip-next-internal-routes-base-path/app/page.tsx
 create mode 100644 test/e2e/middleware-skip-next-internal-routes-base-path/middleware-skip-next-internal-routes-base-path.test.ts
 create mode 100644 test/e2e/middleware-skip-next-internal-routes-base-path/middleware.ts
 create mode 100644 test/e2e/middleware-skip-next-internal-routes-base-path/next.config.js
 create mode 100644 test/e2e/middleware-skip-next-internal-routes-opt-out/app/layout.tsx
 create mode 100644 test/e2e/middleware-skip-next-internal-routes-opt-out/app/page.tsx
 create mode 100644 test/e2e/middleware-skip-next-internal-routes-opt-out/middleware-skip-next-internal-routes-opt-out.test.ts
 create mode 100644 test/e2e/middleware-skip-next-internal-routes-opt-out/middleware.ts
 create mode 100644 test/e2e/middleware-skip-next-internal-routes-opt-out/next.config.js
 create mode 100644 test/e2e/middleware-skip-next-internal-routes/app/layout.tsx
 create mode 100644 test/e2e/middleware-skip-next-internal-routes/app/page.tsx
 create mode 100644 test/e2e/middleware-skip-next-internal-routes/middleware-skip-next-internal-routes.test.ts
 create mode 100644 test/e2e/middleware-skip-next-internal-routes/middleware.ts
 create mode 100644 test/e2e/middleware-skip-next-internal-routes/next.config.js

diff --git a/test/e2e/middleware-skip-next-internal-routes-base-path/app/layout.tsx b/test/e2e/middleware-skip-next-internal-routes-base-path/app/layout.tsx
new file mode 100644
index 00000000000000..08eaa94fdc8896
--- /dev/null
+++ b/test/e2e/middleware-skip-next-internal-routes-base-path/app/layout.tsx
@@ -0,0 +1,11 @@
+export default function RootLayout({
+  children,
+}: {
+  children: React.ReactNode
+}) {
+  return (
+    <html>
+      <body>{children}</body>
+    </html>
+  )
+}
diff --git a/test/e2e/middleware-skip-next-internal-routes-base-path/app/page.tsx b/test/e2e/middleware-skip-next-internal-routes-base-path/app/page.tsx
new file mode 100644
index 00000000000000..ff7159d9149fee
--- /dev/null
+++ b/test/e2e/middleware-skip-next-internal-routes-base-path/app/page.tsx
@@ -0,0 +1,3 @@
+export default function Page() {
+  return <p>hello world</p>
+}
diff --git a/test/e2e/middleware-skip-next-internal-routes-base-path/middleware-skip-next-internal-routes-base-path.test.ts b/test/e2e/middleware-skip-next-internal-routes-base-path/middleware-skip-next-internal-routes-base-path.test.ts
new file mode 100644
index 00000000000000..2fb46031a98bf1
--- /dev/null
+++ b/test/e2e/middleware-skip-next-internal-routes-base-path/middleware-skip-next-internal-routes-base-path.test.ts
@@ -0,0 +1,18 @@
+import { nextTestSetup } from 'e2e-utils'
+
+describe('middleware skip Next.js internal routes with base path', () => {
+  const { next } = nextTestSetup({
+    files: __dirname,
+  })
+
+  it('should execute middleware on regular routes', async () => {
+    const res = await next.fetch('/base')
+    expect(res.status).toBe(200)
+    expect(res.headers.get('x-middleware-executed')).toBe('true')
+  })
+
+  it('should NOT execute middleware on _next routes', async () => {
+    const res = await next.fetch('/base/_next/static/chunks/webpack.js')
+    expect(res.headers.get('x-middleware-executed')).toBeFalsy()
+  })
+})
diff --git a/test/e2e/middleware-skip-next-internal-routes-base-path/middleware.ts b/test/e2e/middleware-skip-next-internal-routes-base-path/middleware.ts
new file mode 100644
index 00000000000000..97426e940d1f77
--- /dev/null
+++ b/test/e2e/middleware-skip-next-internal-routes-base-path/middleware.ts
@@ -0,0 +1,7 @@
+import { NextResponse } from 'next/server'
+
+export function middleware() {
+  const response = NextResponse.next()
+  response.headers.set('x-middleware-executed', 'true')
+  return response
+}
diff --git a/test/e2e/middleware-skip-next-internal-routes-base-path/next.config.js b/test/e2e/middleware-skip-next-internal-routes-base-path/next.config.js
new file mode 100644
index 00000000000000..fa1d25f445b248
--- /dev/null
+++ b/test/e2e/middleware-skip-next-internal-routes-base-path/next.config.js
@@ -0,0 +1,6 @@
+/** @type {import('next').NextConfig} */
+const nextConfig = {
+  basePath: '/base',
+}
+
+module.exports = nextConfig
diff --git a/test/e2e/middleware-skip-next-internal-routes-opt-out/app/layout.tsx b/test/e2e/middleware-skip-next-internal-routes-opt-out/app/layout.tsx
new file mode 100644
index 00000000000000..08eaa94fdc8896
--- /dev/null
+++ b/test/e2e/middleware-skip-next-internal-routes-opt-out/app/layout.tsx
@@ -0,0 +1,11 @@
+export default function RootLayout({
+  children,
+}: {
+  children: React.ReactNode
+}) {
+  return (
+    <html>
+      <body>{children}</body>
+    </html>
+  )
+}
diff --git a/test/e2e/middleware-skip-next-internal-routes-opt-out/app/page.tsx b/test/e2e/middleware-skip-next-internal-routes-opt-out/app/page.tsx
new file mode 100644
index 00000000000000..ff7159d9149fee
--- /dev/null
+++ b/test/e2e/middleware-skip-next-internal-routes-opt-out/app/page.tsx
@@ -0,0 +1,3 @@
+export default function Page() {
+  return <p>hello world</p>
+}
diff --git a/test/e2e/middleware-skip-next-internal-routes-opt-out/middleware-skip-next-internal-routes-opt-out.test.ts b/test/e2e/middleware-skip-next-internal-routes-opt-out/middleware-skip-next-internal-routes-opt-out.test.ts
new file mode 100644
index 00000000000000..9e4f81c5117423
--- /dev/null
+++ b/test/e2e/middleware-skip-next-internal-routes-opt-out/middleware-skip-next-internal-routes-opt-out.test.ts
@@ -0,0 +1,18 @@
+import { nextTestSetup } from 'e2e-utils'
+
+describe('middleware skip Next.js internal routes (opt-out)', () => {
+  const { next } = nextTestSetup({
+    files: __dirname,
+  })
+
+  it('should execute middleware on regular routes', async () => {
+    const res = await next.fetch('/')
+    expect(res.status).toBe(200)
+    expect(res.headers.get('x-middleware-executed')).toBe('true')
+  })
+
+  it('should ALSO execute middleware on _next routes when opted out', async () => {
+    const res = await next.fetch('/_next/static/chunks/webpack.js')
+    expect(res.headers.get('x-middleware-executed')).toBe('true')
+  })
+})
diff --git a/test/e2e/middleware-skip-next-internal-routes-opt-out/middleware.ts b/test/e2e/middleware-skip-next-internal-routes-opt-out/middleware.ts
new file mode 100644
index 00000000000000..97426e940d1f77
--- /dev/null
+++ b/test/e2e/middleware-skip-next-internal-routes-opt-out/middleware.ts
@@ -0,0 +1,7 @@
+import { NextResponse } from 'next/server'
+
+export function middleware() {
+  const response = NextResponse.next()
+  response.headers.set('x-middleware-executed', 'true')
+  return response
+}
diff --git a/test/e2e/middleware-skip-next-internal-routes-opt-out/next.config.js b/test/e2e/middleware-skip-next-internal-routes-opt-out/next.config.js
new file mode 100644
index 00000000000000..a590bd7b5ce14b
--- /dev/null
+++ b/test/e2e/middleware-skip-next-internal-routes-opt-out/next.config.js
@@ -0,0 +1,6 @@
+/** @type {import('next').NextConfig} */
+const nextConfig = {
+  skipMiddlewareNextInternalRoutes: false,
+}
+
+module.exports = nextConfig
diff --git a/test/e2e/middleware-skip-next-internal-routes/app/layout.tsx b/test/e2e/middleware-skip-next-internal-routes/app/layout.tsx
new file mode 100644
index 00000000000000..08eaa94fdc8896
--- /dev/null
+++ b/test/e2e/middleware-skip-next-internal-routes/app/layout.tsx
@@ -0,0 +1,11 @@
+export default function RootLayout({
+  children,
+}: {
+  children: React.ReactNode
+}) {
+  return (
+    <html>
+      <body>{children}</body>
+    </html>
+  )
+}
diff --git a/test/e2e/middleware-skip-next-internal-routes/app/page.tsx b/test/e2e/middleware-skip-next-internal-routes/app/page.tsx
new file mode 100644
index 00000000000000..ff7159d9149fee
--- /dev/null
+++ b/test/e2e/middleware-skip-next-internal-routes/app/page.tsx
@@ -0,0 +1,3 @@
+export default function Page() {
+  return <p>hello world</p>
+}
diff --git a/test/e2e/middleware-skip-next-internal-routes/middleware-skip-next-internal-routes.test.ts b/test/e2e/middleware-skip-next-internal-routes/middleware-skip-next-internal-routes.test.ts
new file mode 100644
index 00000000000000..9fa90820d5759c
--- /dev/null
+++ b/test/e2e/middleware-skip-next-internal-routes/middleware-skip-next-internal-routes.test.ts
@@ -0,0 +1,18 @@
+import { nextTestSetup } from 'e2e-utils'
+
+describe('middleware skip Next.js internal routes', () => {
+  const { next } = nextTestSetup({
+    files: __dirname,
+  })
+
+  it('should execute middleware on regular routes', async () => {
+    const res = await next.fetch('/')
+    expect(res.status).toBe(200)
+    expect(res.headers.get('x-middleware-executed')).toBe('true')
+  })
+
+  it('should NOT execute middleware on _next routes', async () => {
+    const res = await next.fetch('/_next/static/chunks/webpack.js')
+    expect(res.headers.get('x-middleware-executed')).toBeFalsy()
+  })
+})
diff --git a/test/e2e/middleware-skip-next-internal-routes/middleware.ts b/test/e2e/middleware-skip-next-internal-routes/middleware.ts
new file mode 100644
index 00000000000000..97426e940d1f77
--- /dev/null
+++ b/test/e2e/middleware-skip-next-internal-routes/middleware.ts
@@ -0,0 +1,7 @@
+import { NextResponse } from 'next/server'
+
+export function middleware() {
+  const response = NextResponse.next()
+  response.headers.set('x-middleware-executed', 'true')
+  return response
+}
diff --git a/test/e2e/middleware-skip-next-internal-routes/next.config.js b/test/e2e/middleware-skip-next-internal-routes/next.config.js
new file mode 100644
index 00000000000000..767719fc4fba59
--- /dev/null
+++ b/test/e2e/middleware-skip-next-internal-routes/next.config.js
@@ -0,0 +1,4 @@
+/** @type {import('next').NextConfig} */
+const nextConfig = {}
+
+module.exports = nextConfig

From 7e8609b7b53d9f41a8e86de8e0742b34df66ae7d Mon Sep 17 00:00:00 2001
From: devjiwonchoi <devjiwonchoi@gmail.com>
Date: Tue, 7 Oct 2025 22:34:58 +0200
Subject: [PATCH 3/5] Fix existing tests

---
 test/e2e/middleware-general/test/index.test.ts            | 4 +++-
 test/e2e/middleware-trailing-slash/app/next.config.js     | 2 ++
 test/e2e/skip-trailing-slash-redirect/app/next.config.js  | 2 ++
 test/integration/next-image-new/middleware/next.config.js | 4 ++++
 4 files changed, 11 insertions(+), 1 deletion(-)
 create mode 100644 test/integration/next-image-new/middleware/next.config.js

diff --git a/test/e2e/middleware-general/test/index.test.ts b/test/e2e/middleware-general/test/index.test.ts
index 0d616d10b5132d..3285390b43ca2c 100644
--- a/test/e2e/middleware-general/test/index.test.ts
+++ b/test/e2e/middleware-general/test/index.test.ts
@@ -39,6 +39,8 @@ describe('Middleware Runtime', () => {
           ),
         },
         nextConfig: {
+          // This test needs to intercept internal routes /_next/ (skipped by default)
+          skipMiddlewareNextInternalRoutes: false,
           experimental: {
             webpackBuildWorker: true,
           },
@@ -127,7 +129,7 @@ describe('Middleware Runtime', () => {
             runtime: 'nodejs',
             matchers: [
               {
-                regexp: '^.*$',
+                regexp: '^/.*$',
                 originalSource: '/:path*',
               },
             ],
diff --git a/test/e2e/middleware-trailing-slash/app/next.config.js b/test/e2e/middleware-trailing-slash/app/next.config.js
index 0c482151c3a261..7bbcc25aa2ac67 100644
--- a/test/e2e/middleware-trailing-slash/app/next.config.js
+++ b/test/e2e/middleware-trailing-slash/app/next.config.js
@@ -1,4 +1,6 @@
 module.exports = {
+  // This test needs to intercept internal routes /_next/ (skipped by default)
+  skipMiddlewareNextInternalRoutes: false,
   trailingSlash: true,
   redirects() {
     return [
diff --git a/test/e2e/skip-trailing-slash-redirect/app/next.config.js b/test/e2e/skip-trailing-slash-redirect/app/next.config.js
index 5b0be24a8af11d..ec8f1f73a1db3f 100644
--- a/test/e2e/skip-trailing-slash-redirect/app/next.config.js
+++ b/test/e2e/skip-trailing-slash-redirect/app/next.config.js
@@ -1,5 +1,7 @@
 /** @type {import('next').NextConfig} */
 const nextConfig = {
+  // This test needs to intercept internal routes /_next/ (skipped by default)
+  skipMiddlewareNextInternalRoutes: false,
   skipMiddlewareUrlNormalize: true,
   skipTrailingSlashRedirect: true,
   experimental: {
diff --git a/test/integration/next-image-new/middleware/next.config.js b/test/integration/next-image-new/middleware/next.config.js
new file mode 100644
index 00000000000000..613d90fa882e77
--- /dev/null
+++ b/test/integration/next-image-new/middleware/next.config.js
@@ -0,0 +1,4 @@
+module.exports = {
+  // This test needs to intercept internal routes /_next/ (skipped by default)
+  skipMiddlewareNextInternalRoutes: false,
+}

From b856935f0c4278169a90c3516e8b9fd409cde5fb Mon Sep 17 00:00:00 2001
From: JJ Kasper <jj@jjsweb.site>
Date: Wed, 8 Oct 2025 13:14:26 -0700
Subject: [PATCH 4/5] Apply suggestions from code review

---
 crates/next-api/src/middleware.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/crates/next-api/src/middleware.rs b/crates/next-api/src/middleware.rs
index 696512a4078bd8..4c659310b54b6d 100644
--- a/crates/next-api/src/middleware.rs
+++ b/crates/next-api/src/middleware.rs
@@ -55,7 +55,7 @@ fn get_default_middleware_matcher(
         // route starts with underscore.
         MiddlewareMatcher {
             regexp: Some(rcstr!("^(?!.*\\/\\_next\\/(?!data\\/)).*")),
-            original_source: rcstr!("/:path*"),
+            original_source: rcstr!("'/((?!_next/(?!data/))[^]*)*'"),
             ..Default::default()
         }
     } else {

From a6ad8ae0b698e1b060a0bfb74ffb82fee877df4a Mon Sep 17 00:00:00 2001
From: Jiwon Choi <devjiwonchoi@gmail.com>
Date: Wed, 8 Oct 2025 22:27:13 +0200
Subject: [PATCH 5/5] Remove single quote from regex

Co-authored-by: vercel[bot] <35613825+vercel[bot]@users.noreply.github.com>
---
 crates/next-api/src/middleware.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/crates/next-api/src/middleware.rs b/crates/next-api/src/middleware.rs
index 4c659310b54b6d..ace2d5c0b9adc6 100644
--- a/crates/next-api/src/middleware.rs
+++ b/crates/next-api/src/middleware.rs
@@ -55,7 +55,7 @@ fn get_default_middleware_matcher(
         // route starts with underscore.
         MiddlewareMatcher {
             regexp: Some(rcstr!("^(?!.*\\/\\_next\\/(?!data\\/)).*")),
-            original_source: rcstr!("'/((?!_next/(?!data/))[^]*)*'"),
+            original_source: rcstr!("/((?!_next/(?!data/))[^]*)*"),
             ..Default::default()
         }
     } else {