GitHub Security Advisory: GHSA-fr8x-3vfx-f45h
Package: gix (RUST)
Severity: HIGH (CVSS 0.0)
CWE: CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Vulnerable versions: < 0.83.0
Patched in: 0.83.0

Summary: gix and gitoxide: unvalidated submodule name traverses out of .git/modules and redirects state() / open() to another repository

Details:
## **Summary**
attachments:
[pocs.zip](https://github.com/user-attachments/files/26431422/pocs.zip)

Submodule names coming from `.gitmodules` are exposed as unvalidated names and are later reused to derive the submodule git directory as:

```
<superproject common_dir>/modules/<submodule name>
```

Because the submodule name is joined directly as a filesystem path component, a name such as `../../../escaped-target.git` escapes `.git/modules` after normalization. The current implementation then uses that escaped path in both `state()` and `open()`.

The updated PoC demonstrates the real sink, not just string construction:

- `state()` reports `repository_exists=true` for the traversed path;
- `open()` returns a repository whose normalized `common_dir()` matches the attacker-chosen repository outside `.git/modules`.

## **Root cause analysis**

The relevant flow is:

1. [`gix-submodule/src/access.rs`](https://github.com/GitoxideLabs/gitoxide/blob/v0.52.0/gix-submodule/src/access.rs) exposes unvalidated submodule names from configuration.
2. [`gix/src/submodule/mod.rs`](https://github.com/GitoxideLabs/gitoxide/blob/v0.52.0/gix/src/submodule/mod.rs) derives the git directory by doing `common_dir().join("modules").join(name)` with no confinement check.
3. [`gix/src/submodule/mod.rs`](https://github.com/GitoxideLabs/gitoxide/blob/v0.52.0/gix/src/submodule/mod.rs) uses that derived path during state resolution and repository opening.

There is no normalization-and-confinement step between “submodule name from configuration” and “filesystem path used for repository existence checks / open.” As a result, traversal segments in the submodule name directly influence which repository path is inspected and opened.

## **Reproduce steps**

Use the attached PoC zip that contains the `pocs/` workspace.

1. Unzip the PoC archive.
2. Enter `pocs/F002`.
3. Run:
    
    ```
    cargo run --quiet
    ```
    
4. Compare the output with `pocs/F002/result.txt`.

Key outputs are:

- `submodule_name=../../../escaped-target.git`
- `derived_git_dir_raw=.../.git/modules/../../../escaped-target.git`
- `derived_git_dir_normalized=.../artifacts/escaped-target.git`
- `escaped_target=.../artifacts/escaped-target.git`
- `repository_exists=true`
- `submodule_opened=true`
- `opened_common_dir_normalized=.../artifacts/escaped-target.git`
- `normalized_git_dir_matches_target=true`
- `opened_common_dir_matches_target=true`
- `target_outside_modules_root=true`

These outputs show that gitoxide is not only constructing a traversable path string. It is actually using the escaped path for repository existence checks and for opening a repository object.

## **Impact**

Confirmed impact:

- a malicious submodule name can redirect submodule state inspection away from `.git/modules/<name>` to an attacker-chosen repository path outside `.git/modules`;
- `Submodule::state()` can report repository existence for the wrong repository;
- `Submodule::open()` can return a repository object backed by