# Quoting Boris Cherny

> Source: <https://simonwillison.net/2026/Jul/25/boris-cherny/#atom-everything>
> Published: 2026-07-25 00:42:59+00:00

More than any of these eval scores, what is most exciting to me is something else: Opus 5 is our least prompt injectable model yet. It is a bit buried in the system card, but across PI evals and red teaming, Opus 5 is very hard to prompt inject successfully.

— [Boris Cherny](https://twitter.com/bcherny/status/2080713091688583312), here's that [System Card section](https://www-cdn.anthropic.com/c5fbac3f0b1280a933ebd26d3cb8bb9f5bdeaf48/Claude%20Opus%205%20System%20Card.pdf#page=73), page 73

Tags: [prompt-injection](https://simonwillison.net/tags/prompt-injection), [anthropic](https://simonwillison.net/tags/anthropic), [claude](https://simonwillison.net/tags/claude), [generative-ai](https://simonwillison.net/tags/generative-ai), [ai](https://simonwillison.net/tags/ai), [llms](https://simonwillison.net/tags/llms), [boris-cherny](https://simonwillison.net/tags/boris-cherny)