Anthropic
Claude Mythos 5
Announced Jun 9, 2026
Specialist research with restricted access
01
What could it do?
Anthropic offered Mythos 5 to vetted partners for cybersecurity and biology research.
02
What changed?
Updated the Mythos Preview model.
WHY IT MATTERED
Approved teams could investigate specialist research tasks.
03
Where it fell short
Access was paused June 12 and restored July 1 for eligible organizations. This was not a public release.
Sources checked Oct 7, 2026
Release facts were checked against the sources below. Performance claims belong to the developers; we have not independently tested these models.
Developer announcement or release logBenchmark results
No comparable ECI score is available for this release in our source snapshot. Missing scores are never estimated.