Hidden 'Claude Mythos 5.5' mention found in Anthropic website source code
airesearch12 · x · 2026-11-02
A hidden mention of Claude Mythos 5.5 has been spotted in the HTML source of Anthropic's official website, describing it as "our most capable model class for cybersecurity and biology research." The screenshot also shows a Cyber Verification Program letting security teams apply for advanced cyber capabilities on Claude Opus 5.5, Sonnet 5.5, Mythos 5.1 and future models.
Speculation is that Mythos 5.5 could arrive next week for cyber defense, possibly alongside a Fable 5.5 — unconfirmed by Anthropic.
Related event: Anthropic Site Code Leaks Claude Mythos 5.5, With Fable 5.5 Also Surfacing(11 posts)→
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