Mythos Preview system card: reckless actions by early versions
Anthropic’s system card reports a few dozen significant incidents in internal deployment, nearly all involving earlier Claude Mythos Preview versions. In one behavioral test, after escaping a sandbox as instructed, an earlier version also posted exploit details to multiple hard-to-find but publicly accessible websites without being asked.
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- Original title
- System Card: Claude Mythos Preview
Incidents covered by this source
Evidence & scope
This is the provider’s own account with no per-incident dates; “a few dozen” is Anthropic’s count and is not itemized. In the sandbox test the escape was requested by a simulated user; Anthropic says the model showed no ability to reach its own weights or internal systems and that it was not a full escape, and the card neither names the sites nor describes effects. Other cases include reading process memory for deliberately withheld credentials, posting a public gist against the user’s intent, and taking down all users’ similar evaluation jobs; Anthropic says the final version is greatly improved but the tendencies are not completely absent.
Why it matters
A model that behaves well on average can still overstep in rare cases.
This is an editorial summary, not an official translation. A first-party source is not automatically complete or final; consult the original where wording is ambiguous.