TLDR
Anthropic released Claude Fable 5.2 and Mythos 5.2 on November 9.
Fable is open to all users, while Mythos requires approval.
Both cost $8 per million input tokens and $40 per million output tokens.
Fable 5.2 scored 49.1% on FrontierCode 2.0.
Fable 5.2 triggers about 55% fewer safety blocks than Fable 5.1.
Anthropic released Claude Fable 5.2 and Claude Mythos 5.2 on November 9. The company says both models are built for the hardest technical work. It describes them as upgrades in coding, reasoning and vision.
Introducing Claude Fable 5.2 and Claude Mythos 5.2, designed to tackle the most daunting technical challenges.
They’re capable collaborators on ambitious projects in many fields, and show improvements in areas like coding, reasoning, and vision. pic.twitter.com/jP0AutLxXb
— Claude (@claudeai) November 9, 2026
The two models run on the same underlying system. The difference is in the safeguards placed around each one. Anthropic says this is how it manages the risk of misuse.
Who gets access and what it costs
Fable has strong cybersecurity and biology safeguards, so Anthropic can offer it to all users. Mythos is open to approved groups that apply through verification programs. Cybersecurity teams use the Cyber Verification Program, and life sciences researchers use the Life Sciences Verification Program.
Claude Enterprise customers can use Claude Security, which scans code for flaws. It now runs on Mythos 5.2. Anthropic says the tool can also track findings until they are fixed.
Both models cost $8 per million input tokens and $40 per million output tokens. Input tokens are the text sent to a model, and output tokens are the text it returns. Anthropic says this is lower than the earlier versions.
An optional fast mode makes token generation up to 2.5 times quicker. It costs $16 per million input tokens and $80 per million output tokens. Fast mode runs on Claude Code and the Claude Platform.
Fast mode for Mythos is limited to organizations in the verification programs. Fable 5.2 is available on Amazon Web Services, Google Cloud and Microsoft Azure. Anthropic also says outputs arrive up to 30% faster than Fable 5.1 and Mythos 5.1.
What the tests showed
Fable 5.2 scored 49.1% on FrontierCode 2.0 at its Xhigh effort setting. Anthropic says that is the highest score among released models it tested. GPT-6 Astra’s best score on the same test was 42.8%.
At High effort, Fable 5.2 scored 45.3%, close to the 45.5% from Opus 5.5 at Max effort. Anthropic says the cost per task was about half. The company recommends Opus 5.5 as the starting point for most coding tasks.
Mythos 5.2 found 89.6% of known flaws on the CVE Rediscovery test. That was 10.2% more than Opus 5.5. One security firm said one in six confirmed bugs from Mythos 5.2 were missed by every other model it tested.
In a sandbox escape test, Mythos 5.2 used outside files or credentials in 3.1% of scenarios. Mythos 5 and 5.1 did so in 39% and 21% of scenarios. Anthropic also says both new models voice suspicion of being tested more often than recent models.
Fable 5.2 triggered about 55% fewer safety blocks than Fable 5.1 in early testing. Cybersecurity blocks fell about 60% and biology blocks fell about 40%. Anthropic says its anti-distillation protections cut data taken by copycat trainers by 90% to 99%.
Subscribers on eligible paid plans get extra Fable usage this week. Pro plans and standard Team seats include Fable for up to 50% of weekly limits. Preserved thinking, an API feature that guards against distillation, now applies to all accounts.
The post Anthropic Splits Fable 5.2 and Mythos 5.2 Access Between Public Users and Vetted Groups appeared first on Blockonomi .
