Boris Cherny's Quote: Opus 5 is the Least Susceptible to Prompt Injection
Anthropic
On July 25, 2026, Boris Cherny stated that Opus 5 is the most robust model against prompt injection to date, as evidenced by the results of eval tests and red teaming.
Boris Cherni, cited in a news article from July 25, 2026, notes that the Opus 5 model is the least susceptible to prompt injection among all models released to date. This information is contained in the model's system card on page 73. The results of evaluation tests and red teaming show that Opus 5 is very difficult to successfully attack via prompt injection.
Source: Simon Willison —
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