Claude Mythos 5.2

Not yet independently verified. The specifications for Mythos are Anthropic's own, and the independent measurements we have seen are of Claude Fable 5.2, which Anthropic says is the same underlying model. Access is by application, so no outside test of Mythos itself has been found. We will update this when it can be confirmed, and remove this note.

Organisations have to apply for Claude Mythos 5.2. Anthropic released it on 9 November 2026 alongside Claude Fable 5.2 and describes the two as the same underlying model, with the difference lying in the cyber and biology safeguards that Fable carries. Security work and biomedical research are the intended uses.

Three routes to approval

Access comes through the Cyber Verification Program or the Life Sciences Verification Program, and Enterprise customers can reach it through Claude Security. An organisation doing general software or knowledge work has no route to it and is pointed at Fable or Opus instead. Fast mode, which raises generation speed by up to 2.5 times, is limited to Verification Program organisations.

Pricing level with Fable

Input costs $8 per million tokens and output $40, the same as its sibling. Anthropic says output is up to 30% faster than Claude Mythos 5.1. The model pages give Fable a context of 1,000,000 tokens, 128,000 tokens of output and text and image input, and Anthropic's description of the two as one model implies the same limits here.

What to establish before applying

A buyer weighing Mythos for vulnerability research should read the system card Anthropic published with the release, which covers its prerelease safety testing, and establish what the verification programme requires by way of use-case review. Anthropic says high-stakes risks from misalignment remain low and that the model performed as well as or better than its recent models on most alignment measures. Those statements are the company's own assessment.

Key facts

Maker: Anthropic Released: 9 November 2026 Context window: 1,000,000 tokens Maximum output: 128,000 tokens Input and output: text and image in, text out Price per million tokens: $8 input, $40 output Availability: by application, through the Cyber or Life Sciences Verification Program, or Claude Security for Enterprise customers