Anthropic Reports Data Leak Affecting More Than 100 South Korean Claude Business Accounts

According to ChainCatcher citing Yonhap News Agency and The Washington Post, Anthropic reported to South Korea’s Personal Information Protection Commission that information from more than 100 Korean business accounts for its Claude generative AI service had been exposed. The commission said on November 9 that Anthropic filed the report on October 31. The case is under preliminary review, and no formal investigation has begun. The Washington Post previously reported that U.S. security startup Cathedral accessed Anthropic’s internal systems by exploiting a vulnerability in third-party office software. Anthropic researcher Lydia Hallie said on X that Cathedral accessed account details, including names, email addresses and subscription plans, without authorization, but did not obtain prompts, outputs or payment information. Anthropic said it blocked the affected systems and fixed the vulnerability on the day it learned of the incident.