Version 3.7.0 of webpack-dev-middleware introduces several notable updates compared to version 3.6.2. A key change lies in the dependencies, with mime being updated from version ^2.3.1 to ^2.4.2, and range-parser moving from ^1.0.3 to ^1.2.1, potentially impacting content type handling and range request parsing.
The development dependencies also see significant shifts. Notably, @babel/cli, @babel/core, and @babel/preset-env are introduced in 3.7.0, suggesting increased focus on modern JavaScript compatibility and broader build tooling. The Jest testing framework is upgraded from ^24.5.0 to 24.8.0, alongside the addition of babel-jest and jest-junit, indicating enhancements in testing infrastructure and reporting. ESLint receives an update from ^5.15.3 to 5.16.0, accompanied by enhanced linting configurations via @webpack-contrib/eslint-config-webpack and new plugins such as eslint-plugin-prettier. These changes collectively point to upgraded code quality and style enforcement.
Furthermore, the webpack dependency is upgraded from ^4.29.6 to 4.31.0, ensuring compatibility with the later minor releases of webpack v4 and access to the newest features and bug fixes. Other changes include updates to husky, prettier, lint-staged, @commitlint/cli, and standard-version, reflecting a commitment to modern development workflows, automated code formatting, and standardized release processes. The releaseDate has changed, showing the 3.7.0 has been release the 2019-05-15.
All the vulnerabilities related to the version 3.7.0 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.