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Dark Reader gives users the ability to request style sheets from local web servers

Low severity GitHub Reviewed Published Mar 3, 2026 in darkreader/darkreader • Updated Mar 5, 2026

Package

npm darkreader (npm)

Affected versions

< 4.9.117

Patched versions

4.9.117

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 - Deep Fork Cyber.

References

@alexanderby alexanderby published to darkreader/darkreader Mar 3, 2026
Published to the GitHub Advisory Database Mar 4, 2026
Reviewed Mar 4, 2026
Published by the National Vulnerability Database Mar 4, 2026
Last updated Mar 5, 2026

Severity

Low

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
None
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:N/A:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(4th percentile)

Weaknesses

Exposure of Sensitive Information to an Unauthorized Actor

The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. Learn more on MITRE.

Origin Validation Error

The product does not properly verify that the source of data or communication is valid. Learn more on MITRE.

Exposure of Resource to Wrong Sphere

The product exposes a resource to the wrong control sphere, providing unintended actors with inappropriate access to the resource. Learn more on MITRE.

CVE ID

CVE-2025-68467

GHSA ID

GHSA-x369-mcw8-8rvj

Source code

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