Cathedral, a months-old cybersecurity startup founded by former DOGE staffers, says its AI agents found paths into Anthropic's internal systems in under 12 hours, according to a Washington Post report published Monday, October 26. The way in was not Claude itself but vulnerabilities in unnamed third-party business software Anthropic uses for administrative and sales work, and the test ran under Anthropic's authorized program for outside researchers to report vulnerabilities.

The two sides disagree on how far it went. Cathedral's draft report describes routes to employee salary and job-offer details, meeting transcripts and internal Slack discussions about advanced models. Anthropic confirms access to a limited set of sales, HR and IT systems holding business contact details and basic user-account records, and says customer conversations, Claude responses, source code and model weights were not reached.

Anthropic says its own monitoring flagged some of the activity before Cathedral reported it, that it revoked access the same day, disabled the affected software until vendors confirmed fixes, and reported the incident to federal officials. It also accuses Cathedral of not fully disclosing its activity under the program's rules. A senior administration official who reviewed the draft called the findings a national security concern; Cathedral raised $160 million at a $1.4 billion valuation and holds contracts with three federal agencies.