CVE-2025-68467

/// Technical description

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

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References