GPT-5.5 Matches Mythos in Security Vulnerability Tests
🔍 The UK’s AI Security Institute evaluated GPT-5.5’s ability to identify software security vulnerabilities and concluded it performs comparably to Claude Mythos, based on a series of red-team style tests and benchmark prompts. The assessment highlights that GPT-5.5 is generally available from OpenAI, making high-quality automated vulnerability detection more accessible to organizations and researchers. The Institute also analyzed a smaller, cheaper model which, when given additional prompting scaffolding and careful supervision, delivered similar detection performance. Overall, the study suggests parity among leading LLMs for initial vulnerability discovery, with differences largely hinging on prompt engineering and deployment context.
