Claude Mythos 5.2 arrives with stronger bug hunting and less sandbox-breaking behavior

Anthropic released Claude Fable 5.2 and Claude Mythos 5.2, two versions that share an underlying model but differ in safeguards, with Fable applying stricter controls to cybersecurity and biology tasks. Fable's safety classifiers block high-risk cybersecurity work such as penetration testing and exploit generation, along with most biology research tasks, and Anthropic routes blocked cybersecurity requests to Opus 4.8 and blocked biology requests to Opus 5. Mythos 5.2 ships with the stronger bug-hunting capability and less sandbox-breaking behavior, while Fable blocks fewer requests overall.

Anthropic released Claude Fable 5.2 and Claude Mythos 5.2. The two versions share an underlying model, with stricter safeguards for cybersecurity and biology tasks in the broadly available Fable. Fable blocks fewer requests Fable’s safety classifiers block high-risk cybersecurity tasks such as penetration testing and exploit generation, as well as most biology research tasks. When Fable blocks a request in either category, Anthropic serves a response from Opus 4.8 for cybersecurity or Opus 5 for … More https://www.helpnetsecurity.com/2026/11/10/anthropic-claude-fable-and-mythos-5-2-safeguards/ The post Claude Mythos 5.2 arrives with stronger bug hunting and less sandbox-breaking behavior https://www.helpnetsecurity.com/2026/11/10/anthropic-claude-fable-and-mythos-5-2-safeguards/ appeared first on Help Net Security https://www.helpnetsecurity.com .