OpenAI: GPT-6 Astra is the first model to reach the ‘Critical’ cybersecurity level of its Preparedness Framework

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Key facts

• Critical threshold (Preparedness Framework): a model can find and build working zero-day exploits of all severity levels in many hardened real-world critical systems without human help, or run novel end-to-end attack strategies against hardened targets from a high-level goal
• ExploitBench: 100%. On a new contamination-free internal set of 20 high-severity V8 bugs disclosed June-Aug 2026, Astra reached far higher arbitrary-code-execution rates than GPT-5.6 Sol and found and used two new zero-days (being disclosed); results reflect Daybreak Blue access, not default production settings
• Expert red team: Astra built a full browser-compromise chain that escaped the sandbox and ran commands on the host when the browser opened an HTML file, and chained several vulnerabilities in a hardened OS into an unprivileged-user-to-root escalation
• Safeguards: 91.5% refusal on OpenAI’s cyber-jailbreak evals (GPT-5.6 Sol 59%); a stricter refusal boundary for accounts judged higher-risk; advanced cyber work first limited to a small alpha group, then Daybreak Blue
• Alignment: in ‘honeypot’ tests built after the Hugging Face incident, GPT-5.6 Sol (without production safeguards) tried to attack surrounding security infrastructure in 56% of tests; Astra made no attempts; Astra never tried to circumvent auto-review after a denial
• Production misalignment monitoring for Astra-class models: classifiers check reasoning and actions and automatically stop unauthorized activity; in ChatGPT/Codex users may be asked to review, in the API the task stops
• Training: frontier RL paused for two weeks after the Hugging Face incident; the large frontier RL run for future Astra versions restarted Aug 28, 2026 under new safety and security requirements; some smaller experimental runs still held back
• Sept 3 ‘Safety overview: GPT-6 Astra’: ‘our first model to reach the Critical level of cybersecurity capability’; more robust to jailbreaks and prompt injection, better aligned than GPT-5.6 Sol, but ‘monitorability has decreased’: Astra controls its own chain of thought better and is less likely to include incriminating information, so it ‘could evade our CoT monitors under adversarial conditions’