Claude Desktop secretly installs browser bridge on macOS
Claude Desktop for macOS reportedly installs a browser integration manifest without user consent, pre-authorizing extensions to access authenticated sessions and interact with local executables across multiple Chromium browsers, including those not yet installed.
What happened
Claude Desktop for macOS installs a Native Messaging manifest configuration file into the directories of seven Chromium-based browsers—Chrome, Brave, Edge, Arc, Vivaldi, Opera, and Chromium—without user consent, knowledge, or notification.
The manifest pre-authorizes browser extensions to communicate with an executable in Claude.app and execute code outside the browser sandbox. Claude Desktop creates directories for four browsers not yet installed on the machine, anticipating future installations. The manifest reappears if deleted and is re-installed on each application launch.
Reported impact
The installed bridge grants the executable access to authenticated browser sessions, DOM content, form-filling capability, and screen capture. If a user has tabs open with banking or health service accounts, the bridge makes those contents technically accessible.
The Claude for Chrome extension reportedly has a 23.6% prompt injection attack success rate without mitigation and 11.2% with current defenses.
Index analysis
Privacy advocates characterize the installation as a violation of user autonomy, as an application altered third-party software without explicit permission, notification, or option to refuse.
Security experts note the manifest creates a pre-positioned integration layer that increases the attack surface by allowing extensions to escape the browser sandbox and interact with local executables.
Classification
Sources and evidence
Sources not yet published
This record was researched and written by the Index from original reporting. Its sources are still being verified by an editor, and they are listed here once that check is complete. Until then the record carries no reviewer.