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.
https://www.redmine.org/projects/redmine/wiki/Security_Advisories
https://www.redmine.org/news/131
https://lists.debian.org/debian-lts-announce/2021/05/msg00013.html