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3.4
Dark Reader allows websites to request local files without permission
CVE-2025-68467
GHSA-x369-mcw8-8rvj
Summary
A bug in Dark Reader browser extension allowed websites to request style sheets from local web servers without asking for permission. This could potentially allow malicious websites to access sensitive local files. Users should update to the latest version of Dark Reader (4.9.117 or later) to fix the issue.
What to do
- Update alexanderby darkreader to version 4.9.117.
Affected software
| Vendor | Product | Affected versions | Fix available |
|---|---|---|---|
| alexanderby | darkreader | <= 4.9.117 | 4.9.117 |
Original title
Dark Reader gives users the ability to request style sheets from local web servers
Original description
### Description
Dark Reader versions prior to 4.9.117 included a behavior where a website could request a style sheet from a locally running web server, for example `http://localhost:8080/style.css`, If an address was available and returned a `text/css` content type.
### Patches
The problem was fixed in version 4.9.117, released on December 3, 2025. Most users received the update automatically. Users running manual builds must upgrade to version 4.9.117 or later.
The installed extension version number can be verified in Dark Reader's menu (More > All settings > About), browser settings, `chrome://extensions` or `about:addons` pages.
Users are encouraged not to disable automatic extension updates and use the latest browser version, as browser releases typically include multiple security fixes of varying severity.
### NPM package
The issue does not affect developers using the `darkreader` NPM package for website integration. Developers using the `setFetchMethod()` API must ensure the cross-origin requests are restricted to the intended scope.
### Custom forks
Developers using custom forks of earlier versions of Dark Reader to build other extensions, or integrating it into their apps or browsers, should review their implementation to ensure cross-origin requests are handled securely.
### Acknowledgements
Security research performed by [Brian Carpenter](https://x.com/geeknik) - [Deep Fork Cyber](https://deepforkcyber.com/).
Dark Reader versions prior to 4.9.117 included a behavior where a website could request a style sheet from a locally running web server, for example `http://localhost:8080/style.css`, If an address was available and returned a `text/css` content type.
### Patches
The problem was fixed in version 4.9.117, released on December 3, 2025. Most users received the update automatically. Users running manual builds must upgrade to version 4.9.117 or later.
The installed extension version number can be verified in Dark Reader's menu (More > All settings > About), browser settings, `chrome://extensions` or `about:addons` pages.
Users are encouraged not to disable automatic extension updates and use the latest browser version, as browser releases typically include multiple security fixes of varying severity.
### NPM package
The issue does not affect developers using the `darkreader` NPM package for website integration. Developers using the `setFetchMethod()` API must ensure the cross-origin requests are restricted to the intended scope.
### Custom forks
Developers using custom forks of earlier versions of Dark Reader to build other extensions, or integrating it into their apps or browsers, should review their implementation to ensure cross-origin requests are handled securely.
### Acknowledgements
Security research performed by [Brian Carpenter](https://x.com/geeknik) - [Deep Fork Cyber](https://deepforkcyber.com/).
nvd CVSS3.1
3.4
Vulnerability type
CWE-200
Information Exposure
CWE-346
CWE-668
Published: 4 Mar 2026 · Updated: 13 Mar 2026 · First seen: 6 Mar 2026