diff --git a/packages/vite/src/node/server/middlewares/proxy.ts b/packages/vite/src/node/server/middlewares/proxy.ts
index bf658a9ea7474f..219d15f3c81d21 100644
--- a/packages/vite/src/node/server/middlewares/proxy.ts
+++ b/packages/vite/src/node/server/middlewares/proxy.ts
@@ -154,7 +154,8 @@ export function proxyMiddleware(
             return next()
           } else if (bypassResult === false) {
             debug?.(`bypass: ${req.url} -> 404`)
-            return res.end(404)
+            res.statusCode = 404
+            return res.end()
           }
         }
 
diff --git a/playground/proxy-bypass/__tests__/proxy-hmr.spec.ts b/playground/proxy-bypass/__tests__/proxy-hmr.spec.ts
new file mode 100644
index 00000000000000..093179072a4118
--- /dev/null
+++ b/playground/proxy-bypass/__tests__/proxy-hmr.spec.ts
@@ -0,0 +1,8 @@
+import { expect, test, vi } from 'vitest'
+import { browserLogs } from '~utils'
+
+test('proxy-bypass', async () => {
+  await vi.waitFor(() => {
+    expect(browserLogs.join('\n')).toContain('status of 404 (Not Found)')
+  })
+})
diff --git a/playground/proxy-bypass/index.html b/playground/proxy-bypass/index.html
new file mode 100644
index 00000000000000..f14fde8e428635
--- /dev/null
+++ b/playground/proxy-bypass/index.html
@@ -0,0 +1,2 @@
+root app<br />
+<iframe src="/anotherApp" style="border: 0"></iframe>
diff --git a/playground/proxy-bypass/package.json b/playground/proxy-bypass/package.json
new file mode 100644
index 00000000000000..fa9ecab396977a
--- /dev/null
+++ b/playground/proxy-bypass/package.json
@@ -0,0 +1,11 @@
+{
+  "name": "@vitejs/test-proxy-bypass",
+  "private": true,
+  "version": "0.0.0",
+  "type": "module",
+  "scripts": {
+    "dev": "vite",
+    "build": "vite build",
+    "preview": "vite preview"
+  }
+}
diff --git a/playground/proxy-bypass/vite.config.js b/playground/proxy-bypass/vite.config.js
new file mode 100644
index 00000000000000..13f7a6b42eaafb
--- /dev/null
+++ b/playground/proxy-bypass/vite.config.js
@@ -0,0 +1,15 @@
+import { defineConfig } from 'vite'
+
+export default defineConfig({
+  server: {
+    port: 9606,
+    proxy: {
+      '/anotherApp': {
+        target: 'http://localhost:9607',
+        bypass: () => {
+          return false
+        },
+      },
+    },
+  },
+})
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index e0406f3389b179..a421b405b6f0b6 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -1030,6 +1030,8 @@ importers:
 
   playground/preserve-symlinks/module-a: {}
 
+  playground/proxy-bypass: {}
+
   playground/proxy-hmr: {}
 
   playground/proxy-hmr/other-app: {}