Affected: GOVCERT-LU eml_parser

eml_parser serves as a python module for parsing eml files and returning various information found in the e-mail as well as computed information. Prior to version 2.0.1, the official example script examples/recursively_extract_attachments.py contains a path traversal vulnerability that allows arbitrary file write outside the intended output directory. Attachment filenames extracted from parsed emails are directly used to construct output file paths without any sanitization, allowing an attacker-controlled filename to escape the target directory. This issue has been patched in version 2.0.1.

Affected: PyPI: eml-parser

### Summary The official example script `examples/recursively_extract_attachments.py` contains a path traversal vulnerability that allows arbitrary file write outside the intended output directory. Attachment filenames extracted from parsed emails are directly used to construct output file paths without any sanitization, allowing an attacker-controlled filename to escape the target directory.

### Details File: `examples/recursively_extract_attachments.py` Lines: 61–64 ```python for a in m['attachment']: out_filepath = out_path / a['filename'] # No sanitization print(f'\tWriting attachment: {out_filepath}') with out_filepath.open('wb') as a_out: a_out.write(base64.b64decode(a['raw'])) ```

The value `a['filename']` is attacker-controlled via crafted email attachment headers: ``` Content-Disposition: attachment; filename="../outside/pwned.txt" ```

No path normalization or boundary validation is performed before writing.

### PoC 1. Create a malicious `.eml` file: ``` Content-Disposition: attachment; filename="../outside/pwned.txt" ``` 2. Run the example script: ``` python recursively_extract_attachments.py -p ./emails -o ./safe ``` 3. Expected: `./safe/pwned.txt` 4. Actual: `./outside/pwned.txt` ← written outside the intended directory

Verified on Kali Linux with eml_parser installed via pip in a virtual environment.

### Impact This vulnerability is limited to the **example script only** and does not affect the core eml_parser library. However, as th…