After dissing Anthropic for limiting Mythos, OpenAI restricts access to Cyber, too

In Brief Posted: 12:27 PM PDT · April 30, 2026 Image Credits:ChatGPT After Sam Altman trash-talked Anthropic for gatekeeping its cybersecurity tool Mythos by only releasing it to select users, he confirmed that OpenAI would be doing the same with its competing tool, Cyber. Altman said in a post on X on Thursday that OpenAI will begin rolling out GPT-5.5 Cyber “to critical cyber defenders” in the next few days. OpenAI has an application on its website where people submit information about their credentials and planned use in order to gain access. This version of Cyber can perform such tasks as penetration testing, vulnerability identification (and exploitation), and malware reverse engineering, the application implies. It’s intended to be a toolkit to help a company find security holes and test defenses. The fear is that the kit could be misused by the bad guys. When Anthropic similarly restricted access to Mythos, Altman called the tactic fear-based marketing. Some critics also thought so, saying Anthropic’s rhetoric was overblown. Ironically, an unauthorized group reportedly managed to gain access to Mythos anyway. OpenAI says it’s working to make Cyber more widely available by consulting with the U.S. government and identifying more users with legit