Gray Swan

OpenAI's new GPT-6 Astra model shows major improvements in hallucination rates and jailbreak resistance over predecessor GPT-5.6 Sol, according to OpenAI's system card. However, indirect prompt injection attacks hidden in documents still succeed 8.5% of the time in external testing by Gray Swan, down from 27% but still above rival Claude Opus 5's 4.8% rate.

Anthropic's system card for Claude Opus 5 reports a 0% prompt injection success rate across 129 browser agent test scenarios when Auto Mode is enabled. On Gray Swan's broader indirect prompt injection benchmark, Opus 5 posted a 2.0% attacker success rate after 15 attempts, the lowest among tested frontier models.