What Fronter AI Models Like Mythos and GPT-Cyber Mean for Modern Cybersecurity

(Danny Palmer – Infosecurity Magazine) Landmark announcements by some of the biggest names in artificial intelligence have upended how defenders must think about cybersecurity, vulnerability management and threat detection. In April 2026, Anthropic detailed Mythos Preview, a frontier large language model (LLM) equipped to autonomously find and fix cybersecurity vulnerabilities at scale. Upon launch, Anthropic said that Mythos had already identified thousands of previously undiscovered zero-days. Just days later, OpenAI unveiled GPT-5.4-Cyber, an updated variant of their own GPT-5.4 model fined-tuned to specifically work on cybersecurity problems. The company has since gone onto release an updated version of the model, GPT-5.5-Cyber. For now, both AI companies have restricted their cybersecurity frontier models to a limited audience of approved partners. Mythos Preview is only available to participants of Anthropic’s Project Glasswing. Those confirmed as part of the scheme included some of the biggest names in technology like Amazon Web Services, Apple, Broadcom, Cisco, CrowdStrike, Google, JPMorganChase, the Linux Foundation, Microsoft, NVIDIA and Palo Alto Networks. Meanwhile, OpenAI has limited use of GPT-Cyber to members of its Trusted Access for Cyber (TAC) program. This scheme is based around individual cyber defenders, who must be verified and vetted by OpenAI to gain access. Both Open and Anthropic believe their tools are the future of cybersecurity, but both have been reluctant to go as far as publicly releasing their models. One core consideration is how these AI tools could be exploited in the ‘wrong hands’. Cybercriminals and threat actors are already using AI tools to develop sophisticated phishing campaigns, write malicious code and deploy automated attacks. The same hackers could quickly find ways to abuse these new frontier AI models for their own gain. – What Fronter AI Models Like Mythos & GPT-Cyber Mean for Cybersecurity – Infosecurity Magazine