FrontierThe story, in brief
GPT-5.5 matches Claude Mythos in cyber attack tests, UK AI Security Institute finds
GPT-5.5 just matched Claude Mythos on autonomous cyber attacks. Here's what that means for your AI stack.
The KeyNews take
Why it matters
Two frontier models now demonstrate equivalent capability on adversarial security benchmarks, signaling convergence at the high end of model performance and reshaping competitive positioning in enterprise AI deployments.
The key facts
5 to knowGPT-5.5 autonomously solves full network attack simulation
Performance near parity with Claude Mythos on cyber security benchmarks
Claude Mythos still limited availability; GPT-5.5 already in ChatGPT and API
UK AI Security Institute conducted evaluation
Second model (after Claude Mythos) to achieve autonomous network attack capability
Go to the source
The Decoderthe-decoder.com
Publisher excerpt: OpenAI's GPT-5.5 is the second AI model capable of autonomously solving a full network attack simulation, according to the UK AI Security Institute. Its performance is nearly on par with Anthropic's Claude Mythos, which is still only available to a small group. GPT-5.5, meanwhile, is already…