It refused to run a dangerous option. I wrote it one character shorter, and it ran

GitPython ships a guard against dangerous git options. If your code builds a clone command out of anything that arrived from outside, the library will not let --upload-pack or --config through by default, because both of them execute an arbitrary command. The guard is on out of the box and turns off only with an explicit allow_unsafe_options=True . I handed it --upload-pack=/srv/lab/helper.sh . It refused. I handed it the same thing written differently, -u/srv/lab/helper.sh , and it let it through. The script ran. This is CVE-2026-67324, published on 1 August 2026, scored 9.8 on CVSS 3.1 and 9.3 on CVSS 4.0. Those numbers still come from the CNA that filed it: NVD has not run its own analysis yet, the record sits in status Received, so the score may move. Version 3.1.50 is vulnerable, 3.1.51 is fixed. Below, step by step: the lab, both attempts with real output, the code of the check and why it missed, and what the attack looks like from the outside. Plus the part I find more interesting than the hole itself. This is the third bypass of the same barrier within one year, and all three share a root cause. Why this deserves your attention Almost nobody installs GitPython on purpose. It gets 254 million downloads a month from PyPI against five thousand stars on GitHub, and a two-order gap like that means one thing: it arrives as a passenger. With MLflow, with DVC, with bandit, with semgrep, with half the homegrown scripts that touch repositories in CI. Let me draw the boundary right away, so nobody panics for nothing. Having it installed is harmless on its own. The hole fires only when two conditions hold at the same time: your code calls Repo.clone_from(..., multi_options=[...]) , something an outsider influences ends up inside multi_options . The second one happens more often than it sounds. A repository URL from a web form, build parameters from a config another team edits, a field in a CI job, arguments from a webhook. And if you are leaning on allow_unsafe_options=