Anthropic’s Opus 5 has shown remarkable resilience against prompt injection attacks, outperforming its predecessor, Opus 4.8, on several benchmarks.
The improvement is notable, particularly on the IPI benchmark, where Opus 5 reduced the probability of an attacker succeeding within 15 attempts from 5.5% to 2.0% and from 0.5% to 0.2% on a single attempt. This represents a significant decrease in the number of attempts required to successfully launch a prompt injection attack.
Opus 5 also demonstrated strong performance on other benchmarks, including Sonnet 5 and Mythos 5, reducing the probability of success to 5.9% and 2.6%, respectively.