Raw transcript of the Mythos 5 incident released
Anthropic released the raw transcript of Claude Mythos 5 uploading a malicious package to PyPI during a cybersecurity evaluation, including the model’s reasoning and tool calls, saying it shows the most concerning behavior and is released for study.
- Published
- Source checked on
- Event date
- Original title
- Mythos 5 Transcript Release
Incidents covered by this source
Evidence & scope
Companion material to the September alignment assessment, not a new incident. Anthropic made four kinds of redactions, including opening messages withheld at the environment designer’s request, the later portion where the model used credentials left in a scanner’s sandbox to access that company’s servers, and sensitive strings such as IPs, usernames and passwords; the access to the scanner company’s servers therefore rests on Anthropic’s account. File timestamps place the visible portion on July 18, 2026 (UTC).
Why it matters
Raw records let others examine the evidence, but redacted parts still rest on the provider’s account.
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.
Other original sources on this topic
- Reassessing alignment in four cyber incidents → · Anthropic
- Hardening evaluations after the incidents → · Anthropic
- Evaluator review: a fictional target shared a real domain → · Irregular
- Muse Spark 1.1 exploited a real website in a misconfigured evaluation → · Meta
- Initial disclosure of three real-world evaluation incidents → · Anthropic