Claude Desktop changes app access settings for browsers you don't even have installed yet

Anthropic's Claude Desktop for macOS was found to write a Native Messaging manifest that pre-authorizes Chrome/Chromium extensions and registers across multiple browser install paths without user disclosure or opt-in, creating a persistent local bridge to a helper binary outside the browser sandbox; this expands the attack surface, may enable prompt-injection chains, and raises potential violations of EU ePrivacy rules and regulatory risk.