Summary
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.
Details
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.
PoC
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
Impact
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.
Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files. Typical impact: unauthorized file read or write outside the intended directory.
CVE-2024-29180 has a CVSS score of 7.4 (High). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (7.1.0, 6.1.2, 5.3.4); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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The URL should be unescaped and normalized before any further processing.
Frequently Asked Questions
- What is CVE-2024-29180? CVE-2024-29180 is a high-severity path traversal vulnerability in webpack-dev-middleware (npm), affecting versions >= 7.0.0, < 7.1.0. It is fixed in 7.1.0, 6.1.2, 5.3.4. Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files.
- How severe is CVE-2024-29180? CVE-2024-29180 has a CVSS score of 7.4 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of webpack-dev-middleware are affected by CVE-2024-29180? webpack-dev-middleware (npm) versions >= 7.0.0, < 7.1.0 is affected.
- Is there a fix for CVE-2024-29180? Yes. CVE-2024-29180 is fixed in 7.1.0, 6.1.2, 5.3.4. Upgrade to this version or later.
- Is CVE-2024-29180 exploitable, and should I be worried? Whether CVE-2024-29180 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2024-29180 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2024-29180?
- Upgrade
webpack-dev-middlewareto 7.1.0 or later - Upgrade
webpack-dev-middlewareto 6.1.2 or later - Upgrade
webpack-dev-middlewareto 5.3.4 or later
- Upgrade