Mitigating the risk of prompt injections in browser use

This post details significant advancements in mitigating prompt injection risks for AI agents, specifically within browser-based contexts. It introduces Claude Opus 4.5's improved robustness, new safeguards implemented for the Claude for Chrome extension, and outlines the technical approaches: reinforcement learning for direct model resistance, improved classifiers for scanning untrusted content, and scaled expert human red teaming. The post quantifies progress with a 1% attack success rate and highlights the ongoing nature of this security challenge.