OpenAI calls Astra its most dangerous model yet - watching what it does is only getting harder

The timing is probably no accident. The warning landed the same day rival Anthropic shipped Claude Fable 5.1 and Mythos 5.1, and the two companies have a habit of dropping announcements right around each other's releases. On X, CEO Sam Altman explained why his company isn't shipping anything new: the team spent the summer "sprinting on safety priorities," Astra "has been done training for a while now," and the models after it are being slowed down on purpose. Users on X read that as an excuse from a company falling behind. According to The Information, Anthropic passed OpenAI on revenue this year.

Two zero-days as a side effect of an evaluation

OpenAI backs up the critical rating with a batch of tests. On ExploitBench, a benchmark that measures how well a model builds exploits from known vulnerabilities, Astra scored full marks. Worried those tasks might have leaked into its training data, the company built an internal follow-up stocked with 20 recently disclosed, high-severity V8 vulnerabilities.

There too, Astra beat its predecessor GPT-5.6 Sol by a wide margin, while burning far fewer tokens. It also found two previously unknown zero-day flaws and chained them into a working exploit. OpenAI says it's now reporting those vulnerabilities to the people responsible for the affected software.