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California Researchers Use Claude Mythos to Reveal macOS Privilege Escalation

5/15/2026

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Summary

Story summary

Calif researchers used Anthropic’s Claude Mythos Preview to find a macOS privilege-escalation vulnerability, noting human expertise was essential because Mythos alone could not create the exploit.
They built a kernel privilege-escalation chain in five days after finding two macOS bugs in late April, linking them on macOS 26.4.1 on Apple M5 hardware.
Apple is reviewing Calif’s report and has not confirmed a patch.

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Story summary

Calif researchers used Anthropic’s Claude Mythos Preview to find a macOS privilege-escalation vulnerability, noting human expertise was essential because Mythos alone could not create the exploit.
They built a kernel privilege-escalation chain in five days after finding two macOS bugs in late April, linking them on macOS 26.4.1 on Apple M5 hardware.
Apple is reviewing Calif’s report and has not confirmed a patch.