Arbitrary command execution is possible in Git before 2.20.2, 2.21.x before 2.21.1, 2.22.x before 2.22.2, 2.23.x before 2.23.1, and 2.24.x before 2.24.1 because a "git submodule update" operation can run commands found in the .gitmodules file of a malicious repository.
https://www.debian.org/security/2019/dsa-4581
https://security.gentoo.org/glsa/202003-30
https://raw.githubusercontent.com/git/git/master/Documentation/RelNotes/2.24.1.txt
https://public-inbox.org/git/xmqqr21cqcn9.fsf%40gitster-ct.c.googlers.com/
https://gitlab.com/gitlab-com/gl-security/disclosures/blob/master/003_git_submodule/advisory.md
http://www.openwall.com/lists/oss-security/2019/12/13/1
http://lists.opensuse.org/opensuse-security-announce/2020-05/msg00003.html
http://lists.opensuse.org/opensuse-security-announce/2020-01/msg00056.html