The Opus 5 model is less vulnerable to prompt injection; with a strong defensive combination the success rate is ~0

The Opus 5 language model (Anthropic) performs well in several areas, but the key finding is that tests show this model is the least vulnerable to prompt injection. The combined defenses — strong model alignment, prompt-injection checks, and the layers of Claude Code Auto Mode — reduce the rate of successful injection attempts to approximately 0, significantly increasing the system's security and reliability.