Git before 2.14.5, 2.15.x before 2.15.3, 2.16.x before 2.16.5, 2.17.x before 2.17.2, 2.18.x before 2.18.1, and 2.19.x before 2.19.1 allows remote code execution during processing of a recursive "git clone" of a superproject if a .gitmodules file has a URL field beginning with a '-' character.
https://www.openwall.com/lists/oss-security/2018/10/06/3
https://www.exploit-db.com/exploits/45631/
https://www.exploit-db.com/exploits/45548/
https://www.debian.org/security/2018/dsa-4311
https://usn.ubuntu.com/3791-1/
https://seclists.org/bugtraq/2019/Mar/30
https://marc.info/?l=git&m=153875888916397&w=2
https://github.com/git/git/commit/a124133e1e6ab5c7a9fef6d0e6bcb084e3455b46
https://github.com/git/git/commit/1a7fd1fb2998002da6e9ff2ee46e1bdd25ee8404
https://access.redhat.com/errata/RHSA-2020:0316
https://access.redhat.com/errata/RHSA-2018:3541
https://access.redhat.com/errata/RHSA-2018:3505
https://access.redhat.com/errata/RHSA-2018:3408
http://www.securitytracker.com/id/1041811
http://www.securityfocus.com/bid/107511
http://www.securityfocus.com/bid/105523
http://lists.opensuse.org/opensuse-security-announce/2020-05/msg00003.html