Anthropic Reports Claude Leak to South Korea, Affecting About 100 Enterprise Accounts

November 9 — South Korea's Personal Information Protection Commission said today that Anthropic reported to it on October 31 that information from about 100 South Korean enterprise Claude accounts had been leaked, according to Yonhap. The commission is currently at the preliminary review stage and has not formally opened an investigation. The leak is believed to be related to the security firm Cathedral using a vulnerability in third-party business software to gain unauthorized access to Anthropic's internal systems; potentially exposed information includes account and organization identifiers, names and email addresses. Anthropic employee Lydia Hallie said in a post on X on November 8 that Cathedral accessed account information such as names, email addresses and subscription plans, but did not touch prompts, outputs or payment information, and the company cut off the affected systems on the day of discovery and worked with the vendor to fix the vulnerability.

Previous report: a security company founded by former DOGE members said it breached Anthropic's systems within 12 hours.