Anthropic states Opus 5 is the model in its lineup most difficult to attack via prompt injection.

Anthropic stated in the Opus 5 system card that this model is the least susceptible to prompt injection attacks to date. According to prompt injection evaluation and red teaming test results, Opus 5 demonstrates stronger resistance against malicious prompt injections. Prompt injection is one of the core risks in the field of AI security, where attackers bypass the model's safety constraints through carefully designed inputs to induce the model to perform unintended behaviors. Anthropic disclosed relevant evaluation details on page 73 of the system card.