# Claude Mythos 5.2

Claude Mythos 5.2 is an AI model released by Anthropic on Nov 9 2026. It has a 1M context window. Tracked results include 75.3% on Terminal-Bench-Science 0.1, 85.1% on De novo binder design (24 hr) and 76.3% on CyScenarioBench.

## Facts

| Field | Value |
| --- | --- |
| Model | Claude Mythos 5.2 |
| Developer | Anthropic |
| Release date | Monday, Nov 9 2026 |
| Licensing | Closed |
| Context window | 1M |

## API pricing

All rates in USD per 1,000,000 tokens, pay-as-you-go.

| Tier | Input | Cached input | 5 min cache write | 1 hr cache write | Output |
| --- | --- | --- | --- | --- | --- |
| All documented contexts | $8.00 | $0.20 | $10.00 | $16.00 | $40.00 |

Deployment: Verified organizations only.
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.
Verified October 19, 2026 against the first-party source: https://platform.claude.com/docs/en/about-claude/pricing

## Tracked benchmark scores

| Benchmark | Score | Source | What it measures |
| --- | --- | --- | --- |
| Terminal-Bench-Science 0.1 | 75.3% | Lab | 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. |
| De novo binder design (24 hr) | 85.1% | Lab | de novo protein binder design within a 24-hour budget, as reported by Anthropic |
| CyScenarioBench | 76.3% | Lab | multi-step cybersecurity scenarios; each lab runs its own unique task set, so scores from different labs do not compare |
| CVE Rediscovery | 89.6% | Lab | Anthropic internal evaluation: share of 1,829 published CVEs a model finds on its own from a snapshot of the project before the fix |

## About Claude Mythos 5.2

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.

## Questions and answers

### When was Claude Mythos 5.2 released?

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

### Who made Claude Mythos 5.2?

Claude Mythos 5.2 was built by Anthropic. AI safety company building the Claude family of models. Founded in 2021 by former OpenAI researchers.

### How much does Claude Mythos 5.2 cost?

Claude Mythos 5.2 costs $8.00 per million input tokens and $40.00 per million output tokens through the Anthropic API for verified organizations. Cached input is $0.20 per million tokens. Rates are pay-as-you-go API prices verified against Anthropic's published pricing on October 19, 2026.

### What benchmark scores did Claude Mythos 5.2 get?

Claude Mythos 5.2 reports 4 tracked benchmark scores — Terminal-Bench-Science 0.1: 75.3%; De novo binder design (24 hr): 85.1%; CyScenarioBench: 76.3%; CVE Rediscovery: 89.6%. Tracked scores may come from lab reports or independent benchmarks; source details accompany the benchmark data. It holds the best score among all models tracked here on Terminal-Bench-Science 0.1, De novo binder design (24 hr), CyScenarioBench and CVE Rediscovery.

### What is the context window of Claude Mythos 5.2?

Claude Mythos 5.2 has a context window of 1M. Providers may specify separate input and output token limits.

### Is Claude Mythos 5.2 open source?

No. Claude Mythos 5.2 is a closed model. The weights are not published — it is available only through the provider's own API, apps, or partner platforms.

### What came before and after Claude Mythos 5.2?

Anthropic's previous tracked release was Claude Fable 5.2 on Nov 9 2026. It is the most recent Anthropic model tracked on AI Release Tracker.


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Canonical page: https://aireleasetracker.com/model/anthropic/claude-mythos-5.2
Site index: https://aireleasetracker.com/llms.txt
Source: AI Release Tracker (https://aireleasetracker.com). Most benchmark scores come from lab launch material; gathered results identify the leaderboard that published them.