webpack-dev-middleware Path Traversal vulnerability

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

Prior to versions 7.1.0, 6.1.2, and 5.3.4, the webpack-dev-middleware development middleware for devpack 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. 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`. 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. 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. 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, 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. Starting with fixed versions 7.1.0, 6.1.2, and 5.3.4, the URL is unescaped and normalized before any further processing.

Source published

21 Mar 2024 16:47:53 UTC

Source modified

2 Aug 2024 14:58:57 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · 7.4 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N

Prior to versions 7.1.0, 6.1.2, and 5.3.4, the webpack-dev-middleware development middleware for devpack 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. 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`. 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. 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. 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, 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. Starting with fixed versions 7.1.0, 6.1.2, and 5.3.4, the URL is unescaped and normalized before any further processing.

Source published

Mar 21, 2024, 4:47:53 PM (timezone not stated)

Source modified

Aug 2, 2024, 2:58:57 PM (timezone not stated)

Observed here

11 Nov 2026 00:36:33 UTC

Source terms

ENISA EUVD · source terms and attribution apply

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 3.1 · 7.4 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N

Prior to versions 7.1.0, 6.1.2, and 5.3.4, the webpack-dev-middleware development middleware for devpack 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. 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`. 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. 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. 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, 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. Starting with fixed versions 7.1.0, 6.1.2, and 5.3.4, the URL is unescaped and normalized before any further processing.

Source published

21 Mar 2024 17:15:09 UTC

Source modified

17 Jun 2026 07:22:34 UTC

Observed here

24 Oct 2026 23:17:34 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · [email protected] · Secondary · 7.4 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N

CVSS 3.1 · [email protected] · Primary · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

### Summary _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](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](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. ### Recommendation The URL should be unescaped and normalized before any further processing.

Source published

21 Mar 2024 18:59:28 UTC

Source modified

3 Oct 2026 03:55:42 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N

Publisher rating · HIGH