Model · Multimodal language model
Claude Mythos 5
An invite-only pinned Mythos-class Claude release with a 1M-token context, available through Anthropic's developer API under access programs and documented third-party cloud platforms, without downloadable model weights.
- Developer
- Anthropic
- Distribution
- Developer API · Third-party hosting
- Artifact licensing
- Proprietary access
- License scope
- Reviewed release artifacts and mandatory terms; not an assessment of training code or training data openness.
- Licenses
- Anthropic Commercial Terms of Service
- Boundary
- This record represents the Claude Mythos 5 release identified by the dateless pinned ID claude-mythos-5, the safeguards-lifted variant of the Mythos-class tier delivered by invitation through Project Glasswing and sharing Claude Fable 5's underlying weights. Anthropic's API, Amazon Bedrock, Google Cloud, Microsoft Foundry, Claude Fable 5, Claude Mythos Preview, and later Mythos releases remain separate service or product boundaries.
Risk statements
“CB-1” · Precautionary
We therefore treat Claude Mythos 5 as having CB-1 capabilities and apply commensurate protections: real-time classifier guards, access controls for guard exemptions, a bug bounty program and threat intelligence, rapid-response options for jailbreaks, and security controls against model weight theft.
- Risk areas
- Biological or chemical
- Covers
- The model itself
Read the developer's statement ↗ · 2026-10-07 · Research confidence: High
Anthropic names this release against “CB-1” in biological or chemical capability, as a precaution. The statement covers the model itself. This is the developer's own statement, not an Atlas risk rating.
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