{"id":"GHSA-p538-c434-8v24","title":"GitPython: Arbitrary file truncation via git rev-list --output argument injection in unguarded Commit.count","summary":"GitPython: Arbitrary file truncation via git rev-list --output argument injection in unguarded Commit.count","severity":"medium","cvss":5.4,"cwe":["CWE-88"],"vendor":"GitPython","product":"GitPython","ecosystem":"pip","affected":["GitPython <= 3.1.55"],"patched":["GitPython 3.1.56"],"published":"2026-08-03","updated":"2026-08-03","source":"GHSA","sourceUrl":"https://github.com/advisories/GHSA-p538-c434-8v24","references":[{"url":"https://github.com/gitpython-developers/GitPython/security/advisories/GHSA-p538-c434-8v24"},{"url":"https://github.com/gitpython-developers/GitPython/pull/2184"},{"url":"https://github.com/gitpython-developers/GitPython/commit/38553b6fddc7f6a667cdb45a6762343a08fc72b2"},{"url":"https://github.com/gitpython-developers/GitPython/releases/tag/3.1.56"},{"url":"https://github.com/advisories/GHSA-p538-c434-8v24"}],"tags":["ghsa","pip"],"ingestedAt":"2026-08-03T20:29:32.271Z","slug":"GHSA-p538-c434-8v24","body":"## Overview\n\n## Summary\n`Commit.count()` forwards `**kwargs` into `rev_list` with **no** `check_unsafe_options` guard (the guard exists only in the sibling `iter_items`, commit.py:341). `git rev-list --output=<path>` opens and truncates the target file to 0 bytes before revision parsing, so `count(output='/victim')` destroys/blanks an arbitrary file.\n\n## Root Cause\n`commit.py:290-291` calls `self.repo.git.rev_list(self.hexsha, **kwargs)` with no `check_unsafe_options` and no `allow_unsafe_options` parameter. The sibling `iter_items` (commit.py:341) is guarded; `count` is not. This is a distinct, uncovered sink — GHSA-956x-8gvw-wg5v fixed `iter_commits`/`blame`, not `count`.\n\n## Impact\nDestroy/blank an arbitrary file at process privilege (integrity/availability). Reachability is key-control only (`count` uses `self.hexsha`, not a user ref), and the write is a 0-byte truncation (no content control), so MEDIUM.\n\n## Proof of Concept\n```python\ncommit.count(output='/path/to/victim')   # victim truncated to 0 bytes (verified)\n# control: commit.iter_commits(output=...) raises UnsafeOptionError\n```\n\n## Attack Chain\n1. Entry: app forwards user options -> `commit.count(output='/victim')`. Guard: none. Bypass proof: `iter_commits(output=)` raises UnsafeOptionError; `count(output=)` does not — verified side-by-side.\n2. Sink: `git rev-list <sha> --output=/victim` -> file truncated to 0 bytes. Impact: destroy/blank arbitrary file.\n\n## Bypass Evidence\nLive-verified on HEAD (tag 3.1.53): `count(output=<victim>)` truncated a pre-existing file to 0 bytes; guarded `iter_commits(output=)` raised UnsafeOptionError. Same CNA-accepted \"app forwards user options dict\" model as GHSA-956x-8gvw-wg5v's `archive(**kwargs)`. Uncovered sink, not a duplicate.\n\n## Affected Versions\n`<= 3.1.53`\n\n## Suggested Fix\nAdd `check_unsafe_options` to `Commit.count` (mirroring `iter_items`).\n\n---\nReported by **zx (Jace)** — GitHub: @manus-use\n\n## Affected packages\n\n- `GitPython <= 3.1.55`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `GitPython 3.1.56`","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":29.7,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}