Forensic Summary

The UK's AI Security Institute has evaluated OpenAI's GPT-5.5 for offensive cybersecurity capabilities, finding it comparable to Anthropic's Claude Mythos model in identifying security vulnerabilities. Unlike Mythos, GPT-5.5 is generally available, meaning its vulnerability-discovery capabilities are accessible to a broad population including malicious actors. This raises significant concerns about the proliferation of AI-assisted exploitation tools at scale.

Read the full technical deep-dive on Grid the Grey: https://gridthegrey.com/posts/uk-ai-security-institute-finds-gpt-5-5-matches-claude-mythos-in-cyber/