In Zimbra Collaboration (ZCS) 9.0 through 10.1, a Cross-Site Request Forgery (CSRF) vulnerability exists in the GraphQL endpoint (/service/extension/graphql) of Zimbra webmail due to a lack of CSRF token validation. This allows attackers to perform unauthorized GraphQL operations, such as modifying contacts, changing account settings, and accessing sensitive user data when an authenticated user visits a malicious website.