Exposure of Sensitive Information to an Unauthorized Actor
Open Ticket Request System (OTRS) before 2.2.7 sends e-mail containing a Bcc header field that lists the Blind Carbon Copy recipients, which allows remote attackers to obtain potentially sensitive e-mail address information by reading this field.
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.