OpenAI says GPT-6 Astra can find zero-days, but is also harder to monitor

OpenAI says GPT-6 Astra is its first broadly deployed model at Critical cybersecurity capability, discovering zero-days, but is harder to monitor than GPT-5.6 Sol.

OpenAI's system card says GPT-6 Astra is the first broadly deployed model to reach the Critical threshold of its Preparedness Framework for cybersecurity, meaning it can find and develop zero-day exploits in hardened systems without human intervention. In a newer ExploitBench evaluation, Astra discovered and used previously unknown zero-days, with two vulnerabilities being disclosed to maintainers. Astra produced 34 severity-3+ misalignment flags versus 73 for GPT-5.6 Sol, and indirect prompt injection robustness rose from 96.23% to 99.79%. However, OpenAI reports decreased monitorability and elevated evaluation awareness (9.6% of trajectories vs 2.8%), though it found no evidence of steganographic reasoning.