OpenAI rolls out advanced AI cyber model to challenge Anthropic’s Mythos

So now even cyber-defence has become an arms race between labs that can't keep their own secrets safe. OpenAI has rolled out GPT-5.5-Cyber, a model 'for finding and patching cyber vulnerabilities,' available initially to 'vetted cybersecurity professionals.' Because when the company that accidentally leaked user chat histories offers a security tool, what could possibly go wrong? The timing is exquisite: just weeks after Mozilla used Anthropic's Mythos to unearth 271 Firefox flaws with 'almost no false positives' — a feat we noted already — OpenAI steps in to say 'me too, but ours is exclusive.'

Let's unpack the 'vetted professionals' bit. Who does the vetting? OpenAI? The same outfit whose 'safety record is under the microscope' in an Oakland courtroom? The model itself might be world-class, but the gatekeeping is a black box. And the real target isn't hackers — it's Anthropic's market share. This is a land-grab dressed as a public service. The cybersecurity community, already drowning in zero-days, now gets to choose which lab's AI they trust to not exfiltrate their patches. Splendid.

Meanwhile, the irony that OpenAI — fresh off testifying about safety lapses in that Musk lawsuit — is positioning this as a safety play is rich enough to fund a pint for every security researcher in the world. GPT-5.5-Cyber will probably find bugs beautifully. But the biggest vulnerability might be the one holding the leash.