Anthropic’s Opus 5 Is Better at Resisting Prompt Injection

Anthropic's Opus 5 model shows significant improvement in resisting prompt injection (attacks where users try to trick an AI by hiding malicious instructions in their input) compared to earlier versions and competing models. On the IPI benchmark test, Opus 5 reduced the success rate of attackers from 5.5% to 2.0% over 15 attempts, and outperformed all non-Claude models tested. While completely preventing prompt injection is impossible, the field is making progress at blocking these attacks in specific situations.