Rank #16 of 44·Security·Oct 2026·Cathedral's AI hacking agents (security startup, testing via Anthropic's bug bounty programme)
A startup's AI agents got into Anthropic's sales, HR and IT systems through third-party software, and the two sides dispute how far
Disputed Cathedral says it took under 12 hours and reached salaries, meeting transcripts and Slack messages. Anthropic confirms a limited set of sales, HR and IT systems, says attempts ran over several days, and says Cathedral reported only one of two flaws.
“It didn't pick the front-door lock. It used the side door the HR software left open.”
- The way in was third-party admin and sales software, not Claude
- Anthropic says Claude chats, source code and model weights were not reached
- Anthropic says the attempts ran for days and one of two flaws went unreported; Cathedral says it followed best practice
Anthropic pays outsiders to find holes in its systems. A months-old startup pointed AI agents at it and came back with routes to salaries and Slack messages.
What happened
Cathedral, founded this year by four former DOGE staffers, tested Anthropic through its bug bounty programme. Its draft report says its AI agents, which carry out multi-step tasks without a person approving each move, got in not through Claude but through weaknesses in third-party admin and sales software that many companies use. They found routes to meeting transcripts, salary and job-offer details, and Slack messages about Anthropic's advanced models.
The damage
Anthropic confirms the agents reached a limited set of sales, HR and IT systems holding business contact details and basic account records. It says customer chats with Claude, source code and model weights were never reached, and it has no sign anyone else used the flaws. Its monitoring flagged some of the activity before Cathedral reported it, it cut access the same day and it disabled the affected software until the unnamed vendors fixed it.
How it was caught, and what happened next
The two sides don't agree. Cathedral says it took under 12 hours. Anthropic red-team lead Logan Graham says there were several days of attempts and that Cathedral found two flaws but reported only one. Anthropic says the startup broke the programme's rules; Cathedral says it kept data access to the minimum.
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