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, the Washington Post reported Monday, citing a draft report it reviewed. The company, Cathedral, says it reached meeting transcripts, salary and job-offer details, and Slack messages about Anthropic's most advanced models. The breach was not in Claude itself - the hackers exploited flaws in third-party business software, the kind of administrative and sales tools most companies run. The Post withheld the vendors' names.

Cathedral reported the findings to Anthropic earlier this month through Anthropic's bug bounty program, which pays outside researchers to disclose flaws, and told the affected vendors too. Its draft calls the result evidence of "a serious gap between the offensive capabilities now emerging and the defenses," and says its "data accesses were kept to the absolute minimum." A Cathedral spokeswoman declined to comment to the Post.

Anthropic says the breach was much narrower - that Cathedral reached "a limited set" of its sales, HR and IT systems, including some customer and partner business contacts and basic user account records, and that it cut off the startup's access the same day. It says Claude users' conversations, source code and model weights were not touched, that its own monitoring flagged some of the activity before Cathedral reported it, and that it has no evidence anyone else exploited the flaws, Gizmodo and Tech Startups report. Anthropic also says the researchers spent several days failing to break into its software directly before turning to the vendors' applications.