OpenAI introduces GPT-5.5-Cyber amid regulatory pressure on Anthropic
On June 22, OpenAI officially launched the full version of its specialized model GPT-5.5-Cyber, designed for finding, verifying, and fixing software vulnerabilities. This release comes at a highly significant moment — immediately after the U.S. government imposed export restrictions that forced Anthropic to withdraw its advanced models Claude Fable 5 and Mythos 5.
GPT-5.5-Cyber is a key component of the Daybreak initiative, OpenAI's comprehensive cybersecurity program, which also includes the Codex Security tool and partnerships with leading security companies. The model is not intended for mass use; only verified cybersecurity professionals will have access to it for authorized defensive operations.
Strategic Window of Opportunity
The AI security market landscape changed dramatically after June 9, when Anthropic opened access to two versions of the Claude family. By June 12, the company was forced to disable these models at the request of the U.S. government under export controls. This had serious consequences: on June 23, the law firm Legion filed a lawsuit against the U.S. government, claiming that losing access to Anthropic's models disrupted their legal document preparation tools.
OpenAI chose a fundamentally different approach. The company coordinated all checks with U.S. federal agencies in advance and opened GPT-5.5-Cyber only to verified users. This allowed them to avoid regulatory risks and fill the vacated niche.
Technical Specifications and Benchmarks
According to OpenAI, GPT-5.5-Cyber demonstrates impressive results on specialized tests. On the CyberGym benchmark, the model scored 85.6% compared to 81.8% for standard GPT-5.5. An even more significant gap is observed on ExploitGym: 39.5% versus 25.95%. On the SEC-bench Pro test, results were 69.8% versus 63.1%.
However, it is important to understand the context of these figures. CyberGym focuses on reproducing known vulnerabilities in controlled environments, which does not cover the full spectrum of real-world attacks. Moreover, according to the UK AI Security Institute, in complex multi-step scenarios such as the corporate attack simulation The Last Ones, GPT-5.5-Cyber passed the test in 2 out of 10 attempts, while the updated Mythos Preview from Anthropic succeeded in 6 out of 10 attempts.
Comparison with Competitors
A direct comparison with the withdrawn Anthropic Mythos 5 model shows that GPT-5.5-Cyber outperformed it on CyberGym: 85.6% versus 83.8%. However, on more complex tests such as The Last Ones, the picture is mixed. This suggests that while OpenAI's specialized model is strong in narrow vulnerability reproduction tasks, Anthropic retains an advantage in comprehensive real-world attack scenarios.
Ecosystem and Access Restrictions
OpenAI also launched the Daybreak Cyber Partner Program, which includes giants such as Akamai, Check Point, Cisco, CrowdStrike, IBM, Palo Alto Networks, and others. Additionally, the Patch the Planet initiative for open-source projects was announced, created in collaboration with Trail of Bits and with participation from HackerOne. Among the first participants are cURL, Go, Python, and pyca/cryptography.
My analysis of the situation shows that OpenAI strategically chose the right moment for the launch, filling the vacuum left by Anthropic's departure. However, the AI arms race in cybersecurity is just beginning. While GPT-5.5-Cyber demonstrates superiority in narrow benchmarks, real-world attack scenarios remain with Anthropic. The question is whether OpenAI can catch up with its competitor in complex tasks before regulatory restrictions change the rules of the game again.