Git before 2.19.2 on Linux and UNIX executes commands from the current working directory (as if '.' were at the end of $PATH) in certain cases involving the run_command() API and run-command.c, because there was a dangerous change from execvp to execv during 2017.
https://usn.ubuntu.com/3829-1/
https://security.gentoo.org/glsa/201904-13
https://git.kernel.org/pub/scm/git/git.git/tree/Documentation/RelNotes/2.19.2.txt
https://git.kernel.org/pub/scm/git/git.git/commit/?id=321fd82389742398d2924640ce3a61791fd27d60
https://access.redhat.com/errata/RHSA-2018:3800