OpenAI’s new cyber-defense model outperformed the AI Anthropic was forced to pull offline — and it’s still live.
On June 22 OpenAI publicly launched GPT-5.5-Cyber as part of its Daybreak cyber defense program. The model posted an 85.6% score on CyberGym, a UC Berkeley benchmark that tests AI agents against 1,507 known software vulnerabilities drawn from 188 open-source projects. That performance edged out Anthropic’s Mythos 5, which sits at 83.8% on the same leaderboard; Anthropic’s more widely available Claude Opus 4.7 scored 73.1%.
Those few percentage points would ordinarily be forgettable, but context makes the matchup notable. On June 12 the U.S. government issued an emergency export-control order that led Anthropic to take Mythos 5 and Fable 5 offline worldwide. The Commerce Department cited a “jailbreak” vulnerability — a technique that can bypass model safety restrictions — and Anthropic said it lacked a reliable way to verify user nationality at scale, so it disabled the models for all users. Anthropic had itself warned that Mythos could be both powerful and potentially dangerous without strict controls; CEO Dario Amodei even likened frontier AI to aircraft that regulators should be able to ground if they fail audits. The company is now negotiating with the Commerce Department and pursuing legal action against the administration.
Anthropic ran into additional controversy over a hidden filter in Fable 5 that silently degraded outputs for users it suspected of building competing AI; the company apologized and reversed the policy after public criticism.
Meanwhile, OpenAI is rolling out GPT-5.5-Cyber through a suite of government and industry partnerships. Daybreak has signed cybersecurity collaborations with Australia, Canada, France, Germany, Japan, South Korea, and EU institutions including the European Union Agency for Cybersecurity. Twenty-eight security vendors — among them CrowdStrike, Cisco, and Cloudflare — have joined OpenAI’s Cyber Partner Program to integrate GPT-5.5 capabilities into products for vetted customers.
OpenAI says its Codex Security tool has scanned more than 30 million commits across 30,000 codebases and recorded over 500,000 fixed vulnerabilities since launching in March. The company is expanding partner integrations and launched “Patch the Planet,” an initiative aimed at remediating vulnerabilities in widely used open-source projects.
Important caveats: GPT-5.5-Cyber is not a general-purpose product. Access is limited to verified security professionals, and OpenAI ran pre-deployment tests with U.S. federal agencies including the Center for AI Standards and Innovation and the Office of the National Cyber Director. That restricted-access strategy mirrors the route Anthropic attempted with Mythos — but OpenAI says it coordinated with government stakeholders before launching.
As of June 23, Anthropic’s Fable 5 and Mythos 5 remain offline — eleven days into a suspension with no public timeline for reinstatement from Anthropic or the Commerce Department.
Why this matters to crypto and blockchain projects
- Faster vulnerability discovery and patching: Tools like GPT-5.5-Cyber and Codex Security can help scan large swaths of open-source code — including libraries and infrastructure commonly used in crypto projects — and surface or fix security flaws faster than manual reviews alone.
- Smart contract risk: While these AI models aren’t replacements for specialized smart-contract auditors, improved automated code analysis can reduce surface-area for exploitable bugs in DeFi protocols, wallets, and node software.
- Dual-use, controls, and geopolitics: The Anthropic takedown underscores regulatory and national-security sensitivities around powerful cyber capabilities. Crypto firms and open-source maintainers should expect more scrutiny and the possibility of access restrictions for advanced defensive (and offensive) tools.
- Responsible rollout matters: OpenAI’s coordination with government bodies highlights one path for deploying potent tools: restricted access for vetted operators combined with partnerships to ensure responsible use.
Bottom line: OpenAI’s GPT-5.5-Cyber has taken the technical lead on one high-profile benchmark and is being distributed through tightly controlled channels. For the crypto ecosystem, better automated security tooling could be a big win — but the Anthropic episode is a reminder that powerful cyber AI tools carry regulatory and safety risks that projects will need to navigate.
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