Claude Desktop on macOS Accused of Silently Preauthorizing Browser Access

Anthropic’s Claude Desktop for macOS has been accused of silently installing Native Messaging manifest files that preauthorize its browser extensions to communicate with a local helper binary across multiple Chromium-based browsers, including Chrome, Brave, Edge, Arc, Vivaldi, and Opera. Researcher Alexander Hanff reported that the manifests can be written even for browsers not currently installed, meaning future Chromium-based browsers added to the system could automatically inherit the trust relationship. The manifests reportedly authorize specific extension IDs to access a local executable outside the browser sandbox, creating a persistent browser-to-local bridge without clear user notification or consent.

Security researchers said the behavior expands the host attack surface because a compromised or maliciously updated authorized extension could potentially trigger out-of-sandbox actions with the user’s privileges. Reports also said Anthropic’s browser integrations are designed to inspect the DOM, extract structured data, fill forms, and use login state, raising concerns that sensitive content such as private messages, banking sessions, and typed credentials could be exposed if the bridge were abused. Commentators disputed labeling the feature as outright "spyware," but agreed that silently deploying the manifests creates significant transparency, privacy, and compliance concerns, including possible issues under the EU ePrivacy Directive and related computer misuse rules; Anthropic had not publicly issued a detailed technical rebuttal in the cited reports.