Interesting. Hope there is any clarification on what "Mythos level" is and why 5.5-cyber doesn't arise to it. Any metric I could come up with (parameters, pre-train compute, benchmark scores, etc.) seems somewhere between imperfect and utterly nonsensical. Pure speculation, but GPT-5 series models including the new 5.5 pre-train appear far closer to Sonnet than Opus or Fable in pure parameter count, so maybe that's it, but the "they do not surpass the bar that Mythos set" line sounds more like there is a believe that Mythos/Fable are more capable in cybersecurity tasks, whereas the data [0] doesn't seem to bare this out. I did not do any cybersecurity assessment of Fable 5 myself, partly due to personal reasons that make that something I'm abstaining from, but my coding evals showed that while task adherence and assessment wise it was neck and neck with 5.5, the task inference was a major jump again (something prior Anthropic models tended to already do incredibly well on) and while that makes it a far better model to work with for UX experiments, I don't see how that translates to cybersecurity, along with the aforementioned publicly available evals by AISI.

Seeing as neither Mythos nor GPT-5.5 had been pre-trained with a particular focus on cybersecurity, this would have to mean any model that benchmarks better than GPT-5.4 or Opus 4.6 on these tasks cannot be used by None-US-Citizens. If such guidance isn't enforced for all US labs, I think that's irrefutable evidence that this isn't about cybersecurity or "the bar that Mythos set"...

[0] https://xcancel.com/AISecurityInst/status/205458976317312633...