Anthropic · OpenAI · Mythos · Donald Trump · GPT · Dario Amodei · Decrypt
OpenAI's GPT-5.5 Cyber AI Beats Anthropic's Banned Mythos Model—And Nobody's Shutting It Down
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OpenAI's cybersecurity model beat the Anthropic Mythos AI model that the U.S. government yanked offline—and it's still up and running.
Key facts
- Anthropic's Mythos 5 and Fable 5 were pulled offline on June 12 after the Donald Trump administration issued an emergency export control directive citing national security
- As of June 23, Fable 5 and Mythos 5 remain offline—eleven days into a suspension with no official restoration date from Anthropic or the Commerce Department
- On June 22, OpenAI announced the full launch of GPT-5.5-Cyber as part of its Daybreak cyber defense program
- Twenty-eight security firms—including CrowdStrike, Cisco, and Cloudflare—have joined its Cyber Partner Program to embed GPT-5.5 into their products for vetted customers
Summary
OpenAI released GPT-5.5-Cyber, a model designed to help find and fix software vulnerabilities faster than previous versions. It outperforms Anthropic’s Mythos on key benchmarks, while Mythos faces a U.S. government ban over national security concerns. The model is being released to trusted defenders with controls, in contrast to Anthropic’s more restricted approach. On June 22, OpenAI announced the full launch of GPT-5.5-Cyber as part of its Daybreak cyber defense program.