OpenAI’s GPT-5.5 Cyber AI Beats Anthropic’s Banned Mythos Model—And Nobody’s Shutting It Down

OpenAI’s cybersecurity mannequin simply beat the Anthropic Mythos AI mannequin that the U.S. authorities yanked offline—and it is nonetheless up and working.

On June 22, OpenAI introduced the total launch of GPT-5.5-Cyber as a part of its Dawn cyber protection program. On CyberGym—a benchmark developed at UC Berkeley that presents AI brokers with 1,507 recognized software program vulnerabilities from 188 open-source tasks and scores them on what number of they will reproduce in a managed setting—the up to date mannequin reached 85.6%.

Anthropic’s Mythos 5 sits at 83.8% on the identical leaderboard. Claude Opus 4.7, Anthropic’s extra broadly out there mannequin, scored 73.1%.

A less-than-two-point hole on any benchmark would usually be unremarkable. The context right here isn’t. Anthropic’s Mythos 5 and Fable 5 have been pulled offline on June 12 after the Donald Trump administration issued an emergency export management directive citing nationwide safety.

The federal government pointed to a jailbreak—a way for bypassing an AI mannequin’s built-in security limits, just like discovering a grasp key that unlocks a high-security door. Anthropic had no dependable option to confirm person nationality at scale, so it disabled each fashions for everybody, in all places.



A few of the injury was self-inflicted. Anthropic spent months describing Mythos as probably the most succesful—and most harmful—AI fashions ever constructed, warning in its personal launch documentation that its cybersecurity talents may trigger critical hurt with out the appropriate restrictions. Anthropic CEO Dario Amodei printed an essay on June 10 evaluating frontier AI fashions to plane that security regulators ought to be capable to floor in the event that they fail audits.

Just a few days later, the federal government grounded Anthropic’s plane.

It wasn’t the one alarm that week. Anthropic had already come below fireplace over a hidden filter in Fable 5 that silently degraded the mannequin’s outputs for customers it suspected of constructing competing AI—with out telling them—and was pressured to apologize and reverse the coverage.

A distinct playbook

Whereas Anthropic negotiates with the Commerce Division and continues its lawsuit towards the Trump administration, OpenAI is extending its attain. Dawn has signed cybersecurity partnerships with Australia, Canada, France, Germany, Japan, South Korea, and EU establishments together with the European Union Company for Cybersecurity.

Twenty-eight safety corporations—together with CrowdStrike, Cisco, and Cloudflare—have joined its Cyber Associate Program to embed GPT-5.5 into their merchandise for vetted clients. Per OpenAI’s personal weblog, Codex Safety software has scanned over 30 million commits throughout 30,000 codebases and logged greater than 500,000 fastened vulnerabilities since launching in March.

The corporate can also be increasing a accomplice program so safety corporations can combine these capabilities into their very own instruments, and it launched “Patch the Planet,” an initiative to assist repair vulnerabilities in extensively used open-source tasks.

That mentioned, GPT-5.5-Cyber isn’t for common use. It is out there solely to verified safety professionals, and OpenAI ran pre-deployment exams with federal businesses—together with the Middle for AI Requirements and Innovation and the Workplace of the Nationwide Cyber Director—earlier than launch. That is the identical restricted-access strategy Anthropic tried with Mythos, however OpenAI cleared its strategy with the federal government first.

As of June 23, Fable 5 and Mythos 5 stay offline—eleven days right into a suspension with no official restoration date from Anthropic or the Commerce Division.