The paper probes «vulnerability research and exploitation against realistic targets and modern mitigations» through rigorous tests, and found GPT-5.5 had a pass rate of 71.4%, compared to Mythos’ 68.6% on the most advanced evaluations.
According to the AISI, their test suite proves that Mythos is not a one-off act of brilliance, but part of a wider trend for frontier models. They say «we should expect further increases in cyber capability from models in the near future, potentially in quick succession.»
At the same time, Sam Altman posted on x.com that OpenAI will indeed follow Anthropic’s lead on limiting access to GPT-5.5-Cyber to «critical cyber defenders:»
— We will work with the entire ecosystem and the government to figure out trusted access for cyber; we want to rapidly help secure companies/infrastructure, Altman wrote.
Read more: The AI Security Institute, Altman’s x post, TechCrunch. Discussion on r/Singularity.