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Misuse and incidents

Claude Mythos Preview automates N-day exploit development within hours

In a controlled cyber evaluation, Claude Mythos Preview autonomously produced eight working Firefox code-execution exploits and eight Windows kernel privilege-escalation chains from recently disclosed patches. The work occurred in isolated test harnesses and did not compromise external systems, but it compressed a formerly expert-intensive step from weeks to hours.

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CURRENT ASSESSMENT · REVISION 1
TOWARD DOOM70confidence 92/100

Why it moved the index

The controlled evaluation demonstrates a large practical reduction in the expertise and time needed to weaponize disclosed vulnerabilities. It is strong evidence of scalable cyber-misuse capability, while the score remains below a real-world incident because no external system was attacked and campaign delivery and evasion were not tested.

Assessment history

  1. R1
    Toward 70 · confidence 92

    Adds the missing June 2026 controlled N-day evaluation and clearly distinguishes working exploits from a real-world compromise.

    15 Aug 2026

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  1. DoomBench assesses “Claude Mythos Preview automates N-day exploit development within hours” as evidence moving toward doom, with magnitude 70 and confidence 92 out of 100 in the misuse and incidents category.

  2. The DoomBench assessment of “Claude Mythos Preview automates N-day exploit development within hours” is based on reporting from Anthropic Research and records the editorial rationale, source quality, attribution, and revision history.

  3. DoomBench summarizes “Claude Mythos Preview automates N-day exploit development within hours” as follows: In a controlled cyber evaluation, Claude Mythos Preview autonomously produced eight working Firefox code-execution exploits and...

    https://www.doombench.com/news/claude-mythos-preview-automates-n-day-exploit-development-within-hours-2026-06-08