wger Vulnerable to IDOR: Authenticated Users Can Read Any User's Private Workout Session Data via Template Routine API
Summary
Any authenticated user can read another user's private workout session notes, exercise history, and training statistics by calling the /logs/ and /stats/ actions on a routine they do not own.
The RoutinePermission class grants read access to any authenticated user when a routine has is_template=True, regardless of ownership. The /logs/ and /stats/ API actions use the same permission check but return the routine owner's personal training data instead of the requesting user's data, creating an insecure direct object reference (IDOR).
An attacker with a free account can enumerate all public template routine IDs via GET /api/v2/routine/?is_template=true, then call
GET /api/v2/routine/{id}/logs/ and GET /api/v2/routine/{id}/stats/ to access the owner's private health data including workout notes, weights, repetitions, and performance statistics.
Description
wger exposes a REST API endpoint that allows any authenticated user to retrieve the private workout session notes, exercise logs, and training statistics belonging to another user, as long as that user has at least one routine marked as a public template.
The vulnerability exists in RoutineViewSet (wger/manager/api/views.py). The view defines two custom actions /logs/ and /stats/ that are intended to return data for the requesting user's own training history within a routine. However, the underlying permission check (RoutinePermission.has_object_permission) grants read access to any authenticated user when the routine has is_template=True, regardless of ownership. When the /logs/ or /stats/ actions are invoked against a routine the attacker does not own, they return the owner's private workout history, not the attacker's.
Root Cause
File: wger/manager/api/permissions.py, lines 30–41
```python
def has_object_permission(self, request, view, obj):
if obj.user == request.user:
return True
if obj.is_template: # ← any template is readable
return request.method in permissions.SAFE_METHODS # by any authenticated user
return False
```
File: wger/manager/api/views.py, lines 173–199
```python
@action(detail=True, url_path='logs')
def logs(self, request, pk):
out = LogDisplaySerializer(
self.get_object().logs_display(), # ← returns OWNER's logs, not request.user's
many=True,
).data
return Response(out)
@action(detail=True, url_path='stats')
def stats(self, request, pk):
out = LogStatsDataSerializer(
self.get_object().calculate_log_statistics() # ← owner's statistics
).data
return Response(out)
```
self.get_object() retrieves the routine belonging to the owner (e.g., user A). Since is_template=True passes the permission check for any authenticated user, the attacker's request reaches logs_display() and calculate_log_statistics(), which return the owner's workout history, not the attacker's.
The intended behavior is that templates are public workout *plans* (exercise structure, sets, reps), but the /logs/ and /stats/ actions expose the *owner's personal training history* logged against that plan.
Impact
An authenticated attacker can:
1. Enumerate all public template routines across all users:
GET /api/v2/routine/?is_template=true&is_public=true
2. Read private workout session notes (freeform text entered by the victim after each workout session)
3. Read full workout history including exercise names, weights, repetitions, and dates
4. Read training statistics including volume, intensity, and set counts per muscle group and mesocycle
This data is health-related and personal. Under GDPR and similar regulations, unauthorized access to personal health data constitutes a data breach.
Proof of Concept
Scenario
There are two users in the system:
- alice : a regular wger user who has been using the platform for months. She created a routine called "My 5/3/1 Program" and marked it as a public template so others can copy her exercise structure. She logs all her workouts with personal notes after each session.
- bob : a second registered user who has never interacted with alice's account.
The attack:
Bob calls the routine listing endpoint to find all public templates. He gets back alice's routine ID. He then calls /api/v2/routine/{id}/logs/ an endpoint that should only show his own logs but instead receives alice's full workout history, including all her session notes ("Felt strong today, PR on squat"), weights, and performance data.
Bob does not need to know alice's username. He only needs her routine ID, which is a sequential integer discoverable by iterating ?is_template=true.
Step-by-step
1. Bob registers a free account on the wger instance and obtains a JWT access token via
