Exposure of Sensitive Information to an Unauthorized Actor
Fat Free CRM before 0.12.1 does not restrict JSON serialization, which allows remote attackers to obtain sensitive information via a direct request, as demonstrated by a request for users/1.json.
CWE-200 - Information Exposure
An information exposure vulnerability is categorized as an information flow (IF) weakness, which can potentially allow unauthorized access to otherwise classified information in the application, such as confidential personal information (demographics, financials, health records, etc.), business secrets, and the application's internal environment.