Webpack-dev-middleware version 1.12.2 represents a minor update over its predecessor, version 1.12.1, primarily distinguished by a subtle adjustment in its dependency management. While both versions share the core functionality of serving live webpack bundles to a directory, facilitating faster development workflows by enabling hot-reloading and on-the-fly compilation, they exhibit a notable difference in their declared dependencies. Version 1.12.2 specifies mime version ^1.5.0, while version 1.12.1 relies on mime version ^1.4.1. This shift suggests a potential update in MIME type handling, possibly to accommodate newer file types or address security vulnerabilities associated with older MIME type definitions.
For developers considering adopting or upgrading to version 1.12.2, this change in the mime dependency warrants attention. Developers should ensure that this update doesn't introduce any compatibility issues within their projects, particularly if they rely on specific MIME type behaviors. Although the core functionality remains consistent between the two versions, staying up-to-date with the latest patch releases is generally recommended, as these often include bug fixes and minor improvements that can enhance the overall development experience. Both versions maintain compatibility with Webpack versions 1, 2, and 3 as peer dependencies which ensures a smooth integration in most of the existing projects.
All the vulnerabilities related to the version 1.12.2 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.