Redmine before 3.2.9, 3.3.x before 3.3.6, and 3.4.x before 3.4.4 does not block the --config and --debugger flags to the Mercurial hg program, which allows remote attackers to execute arbitrary commands (through the Mercurial adapter) via vectors involving a branch whose name begins with a --config= or --debugger= substring, a related issue to CVE-2017-17536.
In Redmine before 3.2.7 and 3.3.x before 3.3.4, the reminders function in app/models/mailer.rb does not check whether an issue is visible, which allows remote authenticated users to obtain sensitive information by reading e-mail reminder messages.
In Redmine before 3.2.8, 3.3.x before 3.3.5, and 3.4.x before 3.4.3, XSS exists in app/helpers/application_helper.rb via a multi-value field with a crafted value that is mishandled during rendering of issue history.
In Redmine before 3.2.8, 3.3.x before 3.3.5, and 3.4.x before 3.4.3, XSS exists in app/helpers/queries_helper.rb via a multi-value field with a crafted value that is mishandled during rendering of an issue list.
In Redmine before 3.2.6 and 3.3.x before 3.3.3, remote attackers can obtain sensitive information (password reset tokens) by reading a Referer log, because account/lost_password does not use a redirect.