OpenAI has revealed a new AI model named GPT-5.4-Cyber. Comparable to Anthropic’s Claude Mythos, this latest “cyber-permissive” iteration of its GPT-5.4 is designed for defensive cybersecurity and is not intended for public usage.
## OpenAI’s Latest Variant Aims to Set the Stage for More Advanced Models Ahead
OpenAI asserts that its new GPT-5.4-Cyber variant of GPT-5.4 is tailored to set the groundwork for more advanced models expected later this year.
> “To prepare for increasingly advanced models from OpenAI over the coming months, we are refining our models specifically for defensive cybersecurity applications, beginning today with a variant of GPT‑5.4 designed to be cyber-permissive: GPT‑5.4‑Cyber.”
Access to GPT-5.4-Cyber is restricted to “the highest tier” of users who can verify their status as cybersecurity defenders.
## Authorized Access for Cyber is Necessary for Employing GPT-5.4-Cyber
OpenAI clarifies that GPT-5.4-Cyber is “deliberately fine-tuned for enhanced cyber capabilities and with fewer restrictions on capabilities.”
> “This is a version of GPT‑5.4 that reduces the refusal threshold for legitimate cybersecurity tasks and enables new features for sophisticated defensive workflows, including binary reverse engineering capabilities that allow security experts to scrutinize compiled software for malware risks, vulnerabilities, and security strength without requiring access to its source code.”
Due to its more permissive design, the model will first be released in a limited, iterative manner to approved security vendors, organizations, and researchers. This deployment is part of an expanded version of Trusted Access for Cyber, a cybersecurity initiative initiated by OpenAI earlier this year. The company emphasizes two avenues for obtaining access to Trusted Access for Cyber.
For more details, you can explore TAC [here](https://openai.com/index/trusted-access-for-cyber/) and GPT-5.4-Cyber [here](https://openai.com/index/scaling-trusted-access-for-cyber-defense/).
OpenAI has also recently launched a new version of its Pro plan targeted at Codex users.