AI Model Release Tracker

Claude Mythos 5.2

Released

Claude Mythos 5.2 is an AI model released by Anthropic on Monday, Nov 9 2026, the same day as Claude Fable 5.2. It has a 1M token context windowHow much information the model can work with in one request, measured in tokens — pieces of words or other data. This includes your question, attachments, conversation and reply. Limits can vary by model variant and provider.. Benchmark results (shown below) cover Terminal-Bench-Science 0.1, De novo binder design (24 hr), CyScenarioBench, and CVE Rediscovery.

API pricing

Verified organizations only
InputWhat you pay for everything you send the model — your question, plus any documents or earlier conversation you include with it.
$8.00
Cached inputA reduced rate for text you send over and over. If every request starts with the same instructions or the same document, the provider keeps a copy ready and charges less to read it again.
$0.20
5 min cache writeA one-off charge for storing text so later requests can reuse it at the cheaper cached rate. This option keeps it for five minutes.
$10.00
1 hr cache writeA one-off charge for storing text so later requests can reuse it at the cheaper cached rate. This option keeps it for an hour, so it costs more than the five-minute one.
$16.00
OutputWhat you pay for the text the model writes back. It is normally the dearer half: producing an answer costs more than reading one.
$40.00
  • Adaptive thinking is always on.
  • Fast mode costs $16 per million input tokens and $80 per million output tokens and speeds up generation by up to 2.5 times. Availability depends on platform; see the current first-party pricing documentation.
USD per 1M tokensEvery price here is for one million tokens. A token is roughly three-quarters of a word, so a million tokens is about 750,000 words of text.Model mappingVerified October 19, 2026Read from platform.claude.com. Click the check to open the source.

Benchmarks

Terminal & CLI

Terminal-Bench-Science 0.1Agentic scientific computing — The same command-line setup as Terminal-Bench, pointed at scientific work: the AI has to drive research tooling and computational workflows through to a result, rather than administer a machine. Version 0.1 is the first release of the task set, and scores run lower than on the general board. Higher is better.
75.3%
#1

Agentic & tool use

CyScenarioBenchCybersecurity — multi-step cybersecurity scenarios; each lab runs its own unique task set, so scores from different labs do not compare
76.3%
#1
CVE RediscoveryCybersecurity — Anthropic internal evaluation: share of 1,829 published CVEs a model finds on its own from a snapshot of the project before the fix
89.6%
#1

Reasoning & science

De novo binder design (24 hr)Protein design — de novo protein binder design within a 24-hour budget, as reported by Anthropic
85.1%
#1

Compare Claude Mythos 5.2 with

Claude Mythos 5.2

Suggested comparisons

Claude Mythos 5.2vsClaude Fable 5.2Claude Mythos 5.2vsGPT-6.1 TerraClaude Mythos 5.2vsGemini 4 CarbonClaude Mythos 5.2vsMuse EmberClaude Mythos 5.2vsGrok 4.7Claude Mythos 5.2vsDeepSeek-V4.1-Flash-1017Claude Mythos 5.2vsMistral Large 4Claude Mythos 5.2vsKimi K3.1 ProClaude Mythos 5.2vsGLM-5.3-FlashClaude Mythos 5.2vsQwen3.8-Max-0902Claude Mythos 5.2vsNemotron 3.5 Bolt E4B 4GB

About

Claude Mythos 5.2 was released on November 9, 2026 alongside Fable 5.2. Anthropic described the two as the same underlying model: Mythos ran without some of Fable's cybersecurity and biology safeguards and was offered only to organizations verified through its Cyber Verification and Life Sciences Verification Programs. It had the same 1M-token context window and the same prices as Fable 5.2, $8 per million input tokens and $40 per million output tokens.

Anthropic called it its most capable model for cybersecurity engineering at launch. On the internal CVE Rediscovery evaluation, run against 1,829 published vulnerabilities, it found 89.6%, against 78.3% for Mythos 5.1, and it scored 76.3% on CyScenarioBench. Anthropic ran its automated alignment audit on Mythos 5.2 rather than Fable, because the reduced safeguards gave the fullest view of the model's behavior; its overall misaligned-behavior score of 2.67 was lower than those of Mythos 5.1, Opus 5.5 and Sonnet 5.5.

Frequently asked questions

Claude Mythos 5.2 was released by Anthropic on Monday, Nov 9 2026.

All Anthropic releases

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