Claude Fable 5.2 vs Mythos 5.2: differences and access

Claude Fable 5.2 vs Mythos 5.2: which one should you use?

Updated 2026-11-09. Official Anthropic sources.

Quick answer

Claude Fable 5.2 and Claude Mythos 5.2 are the same underlying model at the same price, $8 input and $40 output per million tokens. Fable 5.2 has cybersecurity and biology safeguards and is open to every paid plan and the API. Mythos 5.2 drops those blocks and is limited to verified organizations. Pick Fable 5.2 unless you run security or life sciences work and can get verified.

	Claude Fable 5.2	Claude Mythos 5.2
Who can use it	Anyone on a paid Claude plan or the API	Verified organizations only
API model ID	claude-fable-5-2	claude-mythos-5-2
Price per 1M tokens	$8 input, $40 output	$8 input, $40 output
Fast mode	$16 input, $80 output	$16 input, $80 output, verified organizations only
Context / max output	1M / 128K tokens	1M / 128K tokens
Cyber and biology safeguards	On: blocks penetration testing, exploit generation, most research biology	Off for verified work
Claude plans	Pro (usage credits), Max, Ultra, Team, Enterprise	Not on Pro, Max or Ultra. Enterprise via Claude Security
CVE Rediscovery (Anthropic-reported)	Not listed (blocked tasks)	89.6%

Same model, different guardrails

Anthropic says plainly that Claude Fable and Claude Mythos "are the same underlying model" in its launch post. Fable ships with classifiers that block high-risk cybersecurity work, such as penetration testing and exploit generation, and most research biology. When Fable blocks a query, the answer comes from Opus 4.8 (cyber) or Opus 5 (biology) instead. Mythos removes those blocks for vetted organizations.

Everything else matches: the price, the 1M token context window, the 128K output cap and the benchmark scores outside security and biology. Anthropic reports 74.6% for Fable 5.2 and 75.3% for Mythos 5.2 on Terminal-Bench-Science, close enough to call even.

How to get Claude Mythos 5.2 access

Apply to the program that fits your work. Cybersecurity teams go through the Cyber Verification Program. Life sciences researchers go through the Life Sciences Verification Program. Claude Enterprise customers can also use Mythos 5.2 inside Claude Security, which scans codebases for vulnerabilities, even without joining a program. There is no checkbox on Pro, Max or Ultra that unlocks it.

Where Mythos 5.2 pulls ahead

Security work. Anthropic reports 76.3% on CyScenarioBench (Mythos 5.1: 61.7%) and 89.6% on CVE Rediscovery (Mythos 5.1: 78.3%). It says Mythos 5.2 found 10.2% more vulnerabilities than Opus 5.5 and 14.4% more than Mythos 5.1 on CVE Rediscovery. These are Anthropic's numbers, not ours.

Fable 5.2 also blocks less than before. Anthropic measured about 55% fewer blocks than Fable 5.1 in early testing: about 60% fewer in cybersecurity and 40% fewer in biology.

Verdict

Fable 5.2 wins for almost everyone, because it is the one you can actually use, at the same price. Mythos 5.2 wins only for verified security and life sciences teams whose work Fable would block.

Full launch coverage: Claude Fable 5.2 and Mythos 5.2: prices, limits and what changed.

Sources

FAQ

What is the difference between Claude Fable 5.2 and Mythos 5.2?

They are the same underlying model, per Anthropic. Fable 5.2 blocks high-risk cybersecurity and most research biology tasks. Mythos 5.2 drops those blocks for verified organizations.

Is Claude Mythos 5.2 better than Fable 5.2?

Only for security and biology work that Fable blocks. On other tasks they are the same model, at the same $8 input and $40 output per million tokens.

How do I get access to Claude Mythos?

Apply through Anthropic's Cyber Verification Program or Life Sciences Verification Program. Claude Enterprise customers can also use it through Claude Security.

Is Claude Mythos 5.2 on Claude Max or Ultra?

No. Mythos 5.2 is limited to verified organizations. Max and Ultra include Fable 5.2, up to 50% of weekly limits.

How much does Claude Mythos 5.2 cost?

$8 per million input tokens and $40 per million output tokens, the same as Fable 5.2. Fast mode is $16 and $80.