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Backport security fix from v5.2.1 to version-4 (non-Chromium browser dev-server vulnerability) #5534

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Backport security fix from v5.2.1 to version-4 (non-Chromium browser dev-server vulnerability) #5534

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c0c647f
Backport security fix from v5.2.1: disable dev client for non-Chromiu…
Wajih-Ul-Hasan Jul 11, 2025
0a08b4b
fix(security): backport dev client access check from v5.2.1 using tru…
Wajih-Ul-Hasan Jul 11, 2025
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12 changes: 12 additions & 0 deletions lib/Server.js
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Original file line number Diff line number Diff line change
@@ -1,5 +1,10 @@
"use strict";

function isTrustedClient(req) {
// Only allow injection if client explicitly identifies itself
return req.headers["webpack-dev-server-client"] === "true";
}

const os = require("os");
const path = require("path");
const url = require("url");
Expand Down Expand Up @@ -2103,6 +2108,13 @@ class Server {
/** @type {import("webpack-dev-middleware").API<Request, Response>}*/
(middleware).waitUntilValid((stats) => {
res.setHeader("Content-Type", "text/html");

if (!isTrustedClient(req)) {
res.statusCode = 403;
res.end("Access denied: Missing required dev server client header.");
return;
}

res.write(
'<!DOCTYPE html><html><head><meta charset="utf-8"/></head><body>'
);
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4 changes: 2 additions & 2 deletions package.json
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
{
"name": "webpack-dev-server",
"version": "4.15.2",
"name": "webpack-dev-server-wajih",
"version": "4.6.0-patched",
"description": "Serves a webpack app. Updates the browser on changes.",
"bin": "bin/webpack-dev-server.js",
"main": "lib/Server.js",
Expand Down