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[ARTICLE · art-72851] src=simonwillison.net ↗ pub= topic=ai-safety verified=true sentiment=↑ positive

Quoting Boris Cherny

Boris Cherny, an Anthropic employee, stated that Claude Opus 5 is the company's least prompt-injectable model yet, based on prompt injection evaluations and red teaming results detailed in the system card on page 73.

read1 min views1 publishedJul 25, 2026

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, here's that System Card section, page 73

Tags: prompt-injection, anthropic, claude, generative-ai, ai, llms, boris-cherny

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