Redmine before 4.0.9, 4.1.x before 4.1.3, and 4.2.x before 4.2.1 allows attackers to bypass the add_issue_notes permission requirement by leveraging the incoming mail handler.

Redmine 4.2.0 and 4.2.1 allow existing user sessions to continue upon enabling two-factor authentication for the user's account, but the intended behavior is for those sessions to be terminated.

Redmine before 4.0.9, 4.1.x before 4.1.3, and 4.2.x before 4.2.1 allows users to circumvent the allowed filename extensions of uploaded attachments.

Redmine before 3.4.13 and 4.x before 4.0.6 mishandles markup data during Textile formatting.