GHSA-2f96-g7mh-g2hx: GitPython: Command Injection via git long-option prefix abbreviation bypass of CVE-2026-42215 blocklist

Command injection via long-option prefix abbreviation bypassing check_unsafe_options (incomplete fix of CVE-2026-42215 / GHSA-rpm5-65cw-6hj4) Component: gitpython-developers/GitPython (PyPI: GitPython) Affected: all versions carrying the 3.1.47 blocklist fix, through current main (verified at commit 20c5e275, 3.1.50-42) CWE: CWE-184 (Incomplete List of Disallowed Inputs) → CWE-78 (OS Command Injection) Severity: inherits the parent CVE-2026-42215 surface; estimated High, ~8.8 (AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H) — final scoring deferred to maintainer/CNA, mirroring the parent. Reporter: hackkim Summary The 3.1.47 fix for CVE-2026-42215 blocks dangerous git options (--upload-pack, --config, -c, -u for clone; --upload-pack for fetch/pull; --receive-pack, --exec for push) so callers cannot reach command-executing options unless they pass allow_unsafe_options=True. The fix canonicalizes an option name along one axis (underscore→hyphen via dashify) and checks it against an exact-match dict. It does not account for git's unambiguous long-option prefix abbreviation. Git accepts any unambiguous prefix of a long option (--upload-p, --upload-pa, --upload-pac all resolve to --upload-pack). So a kwarg key like upload_p canonicalizes to upload-p, misses the blocklist dict, and is emitted to git as --upload-p=<value> → executed as --upload-pack=<value> → command injection, in the default allow_unsafe_options=False configuration. The asymmetry (root cause) git/cmd.py (commit 20c5e275), lines 948-974 @classmethod def _canonicalize_option_name(cls, option): option_name = option.lstrip("-").split("=", 1)[0] option_tokens = option_name.split(None, 1) if not option_tokens: return "" return dashify(option_tokens[0]) # only transform: "_" -> "-" @classmethod def check_unsafe_options(cls, options, unsafe_options): canonical_unsafe_options = {cls._canonicalize_option_name(o): o for o in unsafe_options} for option in options: unsafe_option = canonical_unsafe_options.get(cls._canonic