Improper Input Validation
An issue was discovered in MantisBT through 1.3.14, and 2.0.0. Using a crafted request on bug_report_page.php (modifying the 'm_id' parameter), any user with REPORTER access or above is able to view any private issue's details (summary, description, steps to reproduce, additional information) when cloning it. By checking the 'Copy issue notes' and 'Copy attachments' checkboxes and completing the clone operation, this data also becomes public (except private notes).
CWE-20 - Improper Input Validation
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.