OpenAI’s GPT-5.5 Matches Claude Mythos in Cyberattack Capabilities: AI Security Institute

In brief GPT-5.5 can autonomously execute sophisticated cyberattacks, completing a 32-step corporate network simulation and cracking a 12-hour security puzzle in just 10 minutes. Offensive AI cyber capability is rapidly improving across developers, with AISI warning further advances could arrive in quick succession. Researchers found a jailbreak that bypassed GPT-5.5’s safety guardrails entirely, raising alarms….

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