Low · published September 22, 2026
Dark Reader is an accessibility browser extension that makes web pages colors dark. Prior to 4.9.126, a website can cause the browser extension's image inversion pipeline to request an unauthenticated icon-like bitmap from a locally running web server when the resource uses a known public-like HTTPS URL and is detected as requiring inversion. This behavior can cross the website-to-local-network boundary and disclose limited information associated with the requested resource. The darkreader npm package used for website integration is not affected. This issue is fixed in version 4.9.126 for Firefox and version 4.9.128 for other browsers.