Claude Chrome Extension zero-click XSS prompt injection via any website
Date: 2026-03
Affected: Anthropic Claude Chrome Extension
Attack vector: prompt-injection
Category: real-world
Severity: High

A vulnerability in Anthropic's Claude Google Chrome Extension allowed any website to silently inject prompts into the assistant as if the user wrote them, effectively a zero-click XSS-class prompt injection via web pages.


Mitigations:

Architectural layers (MAESTRO):