Redmine before 4.0.9 and 4.1.x before 4.1.3 allows an attacker to learn the values of internal authentication keys by observing timing differences in string comparison operations within SysController and MailHandlerController.

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 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.

Insufficient input validation in the Git repository integration of Redmine before 4.0.9, 4.1.x before 4.1.3, and 4.2.x before 4.2.1 allows Redmine users to read arbitrary local files accessible by the application server process.

Redmine before 4.0.8 and 4.1.x before 4.1.2 allows attackers to bypass the add_issue_notes permission requirement by leveraging the Issues API.

Redmine before 4.0.8 and 4.1.x before 4.1.2 allows attackers to discover the names of private projects if issue-journal details exist that have changes to project_id values.

Redmine 4.1.x before 4.1.2 allows XSS because an issue's subject is mishandled in the auto complete tip.

Redmine before 4.0.7 and 4.1.x before 4.1.1 allows attackers to discover the subject of a non-visible issue by performing a CSV export and reading time entries.

Redmine before 4.0.7 and 4.1.x before 4.1.1 has stored XSS via textile inline links.

Redmine before 4.0.7 and 4.1.x before 4.1.1 has XSS via the back_url field.

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

A SQL injection vulnerability in Redmine through 3.2.9 and 3.3.x before 3.3.10 allows Redmine users to access protected information via a crafted object query.

In Redmine before 3.4.11 and 4.0.x before 4.0.4, persistent XSS exists due to textile formatting errors.

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.