GitPython versions before 1.2.0.post0_13 contain unguarded forwarding of git command options in IndexFile.checkout() and TagReference.create(), allowing arbitrary file overwrite and arbitrary file read respectively. The checkout method forwards unsafe options to git checkout-index, enabling an attacker to overwrite files anywhere writable by the process using the --prefix option. The tag creation method forwards unsafe options to git tag, allowing reading arbitrary files via the -F/--file option. Both issues arise from missing safety checks on forwarded kwargs. A fix is available in version 1.2.0.post0_13.