GHSA-p538-c434-8v24: GitPython Arbitrary File Truncation Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-p538-c434-8v24",
  "modified" : "2026-08-03T20:23:18Z",
  "published" : "2026-08-03T20:23:17Z",
  "aliases" : [ ],
  "summary" : "GitPython: Arbitrary file truncation via git rev-list --output argument injection in unguarded Commit.count",
  "details" : "## 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",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "GitPython"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "3.1.56"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 3.1.55"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/gitpython-developers/GitPython/security/advisories/GHSA-p538-c434-8v24"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/gitpython-developers/GitPython/pull/2184"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/gitpython-developers/GitPython/commit/38553b6fddc7f6a667cdb45a6762343a08fc72b2"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/gitpython-developers/GitPython"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/gitpython-developers/GitPython/releases/tag/3.1.56"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-88" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-08-03T20:23:17Z",
    "nvd_published_at" : null
  }
}