Summaryinfo

A vulnerability classified as problematic was found in darkreader up to 4.9.116. Affected by this issue is the function setFetchMethod of the component CSS File Parser. Such manipulation leads to information disclosure. This vulnerability is documented as CVE-2025-68467. The attack can be executed remotely. There is not any exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in darkreader up to 4.9.116. It has been rated as problematic. Affected by this issue is the function setFetchMethod of the component CSS File Parser. The manipulation with an unknown input leads to a information disclosure vulnerability. Using CWE to declare the problem leads to CWE-200. The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. Impacted is confidentiality. CVE summarizes:

Dark Reader is an accessibility browser extension that makes web pages colors dark. The dynamic dark mode feature of the extension works by analyzing the colors of web pages found in CSS style sheet files. In order to analyze cross-origin style sheets (stored on websites different from the original web page), Dark Reader requests such files via a background worker, ensuring the request is performed with no credentials and that the content type of the response is a CSS file. Prior to Dark Reader 4.9.117, this style content was assigned to an HTML Style Element in order to parse and loop through style declarations, and also stored in page's Session Storage for performance gains. This could allow a website author to request a style sheet from a locally running web server, for example by having a link pointing to `http[:]//localhost[:]8080/style[.]css`. The brute force of the host name, port and file name would be unlikely due to performance impact, that would cause the browser tab to hang shortly, but it could be possible to request a style sheet if the full URL was known in advance. As per December 18, 2025 there is no known exploit of the issue. The problem has been fixed in version 4.9.117 on December 3, 2025. The style sheets are now parsed using modern Constructed Style Sheets API and the contents of cross-origin style sheets is no longer stored in page's Session Storage. Version 4.9.118 (December 8, 2025) restricts cross-origin requests to localhost aliases, IP addresses, hosts with ports and non-HTTPS resources. The absolute majority of users have received an update 4.1.117 or 4.9.118 automatically within a week. However users must ensure their automatic updates are not blocked and they are using the latest version of the extension by going to chrome://extensions or about:addons pages in browser settings. Users utilizing manual builds must upgrade to version 4.9.118 and above. Developers using `darkreader` NPM package for their own websites are likely not affected, but must ensure the function passed to `setFetchMethod()` for performing cross-origin requests works within the intended scope. Developers using custom forks of earlier versions of Dark Reader to build other extensions or integrating into their apps or browsers must ensure they perform cross-origin requests safely and the responses are not accessible outside of the app or extension.

The advisory is available at github.com. This vulnerability is handled as CVE-2025-68467 since 12/18/2025. The exploitation is known to be difficult. The attack may be launched remotely. No form of authentication is required for exploitation. Successful exploitation requires user interaction by the victim. Technical details are known, but there is no available exploit. This vulnerability is assigned to T1592 by the MITRE ATT&CK project.

Upgrading to version 4.9.117 eliminates this vulnerability.

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Productinfo

Name

• darkreader

Version

• 4.9.116

Website

• Product: https://github.com/darkreader/darkreader/

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