Webpack Dev Middleware helps developers streamline their workflow by serving webpack assets directly from memory during development. Comparing version 1.12.0 with the previous stable version, 1.11.0, reveals subtle but important improvements. Both versions maintain the core functionality of providing a live-reloading bundle to a directory, crucial for fast iteration during development. They share the same core dependencies like "mime", "memory-fs", "range-parser", and "path-is-absolute", ensuring consistent file handling and path manipulation. The development dependencies, including testing frameworks like "mocha", "sinon", and "supertest" used to ensure code quality, are largely identical. However, version 1.12.0 features an updated "sinon" version (2.3.8) compared to version 1.11.0 (2.3.5). This update might include crucial bug fixes or performance improvements beneficial for testing your webpack configurations. Peer dependencies on webpack remain the same, offering compatibility with webpack versions 1, 2, and 3. For developers, this means existing projects using those webpack versions can easily upgrade to either middleware version with minimal disruption. The upgrade to version 1.12.0 primarily provides stability and potential enhancements garnered from the "sinon" update, while maintaining the core advantages of rapid development cycles via in-memory asset serving, making it a worthwhile consideration for those already leveraging webpack-dev-middleware. Ultimately, choosing the newer version allows developers to benefit from the latest refinements and bug fixes in the dependency tree.
All the vulnerabilities related to the version 1.12.0 of the package
Path traversal in webpack-dev-middleware
The webpack-dev-middleware middleware does not validate the supplied URL address sufficiently before returning the local file. It is possible to access any file on the developer's machine.
The middleware can either work with the physical filesystem when reading the files or it can use a virtualized in-memory memfs filesystem. If writeToDisk configuration option is set to true, the physical filesystem is used: https://github.com/webpack/webpack-dev-middleware/blob/7ed24e0b9f53ad1562343f9f517f0f0ad2a70377/src/utils/setupOutputFileSystem.js#L21
The getFilenameFromUrl method is used to parse URL and build the local file path. The public path prefix is stripped from the URL, and the unsecaped path suffix is appended to the outputPath: https://github.com/webpack/webpack-dev-middleware/blob/7ed24e0b9f53ad1562343f9f517f0f0ad2a70377/src/utils/getFilenameFromUrl.js#L82 As the URL is not unescaped and normalized automatically before calling the midlleware, it is possible to use %2e and %2f sequences to perform path traversal attack.
A blank project can be created containing the following configuration file webpack.config.js:
module.exports = { devServer: { devMiddleware: { writeToDisk: true } } };
When started, it is possible to access any local file, e.g. /etc/passwd:
$ curl localhost:8080/public/..%2f..%2f..%2f..%2f../etc/passwd
root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
bin:x:2:2:bin:/bin:/usr/sbin/nologin
sys:x:3:3:sys:/dev:/usr/sbin/nologin
sync:x:4:65534:sync:/bin:/bin/sync
games:x:5:60:games:/usr/games:/usr/sbin/nologin
The developers using webpack-dev-server or webpack-dev-middleware are affected by the issue. When the project is started, an attacker might access any file on the developer's machine and exfiltrate the content (e.g. password, configuration files, private source code, ...).
If the development server is listening on a public IP address (or 0.0.0.0), an attacker on the local network can access the local files without any interaction from the victim (direct connection to the port).
If the server allows access from third-party domains (CORS, Allow-Access-Origin: * ), an attacker can send a malicious link to the victim. When visited, the client side script can connect to the local server and exfiltrate the local files.
The URL should be unescaped and normalized before any further processing.