MantisBT before 1.2.12 does not use an expected default value during decisions about whether a user may modify the status of a bug, which allows remote authenticated users to bypass intended access restrictions and make status changes by leveraging a blank value for a per-status setting.

MantisBT before 1.2.11 does not check the delete_attachments_threshold permission when form_security_validation is set to OFF, which allows remote authenticated users with certain privileges to bypass intended access restrictions and delete arbitrary attachments.

The mc_issue_note_update function in the SOAP API in MantisBT before 1.2.11 does not properly check privileges, which allows remote attackers with bug reporting privileges to edit arbitrary bugnotes via a SOAP request.