Gitk is a Tcl/Tk based Git history browser. Starting with 2.41.0, a Git repository can be crafted in such a way that with some social engineering a user who has cloned the repository can be tricked into running any script (e.g., Bourne shell, Perl, Python, ...) supplied by the attacker by invoking gitk filename, where filename has a particular structure. The script is run with the privileges of the user. This vulnerability is fixed in 2.43.7, 2.44.4, 2.45.4, 2.46.4, 2.47.3, 2.48.2, 2.49.1, and 2.50.
https://github.com/j6t/gitk/security/advisories/GHSA-g4v5-fjv9-mhhc
https://github.com/j6t/gitk/commit/8e3070aa5e331be45d4d03e3be41f84494fce129