wger is a free, open-source workout and fitness manager. Prior to version 2.6, an authenticated attacker can inject arbitrary workout log entries into any other user's `SlotEntry` by supplying the victim's `slot_entry` ID in a `POST /api/v2/workoutlog/` request. The `slot_entry` foreign key is not included in the ownership verification performed by `WorkoutLogViewSet.get_owner_objects()`, so the server accepts and persists the cross-user reference without error. Because `SlotEntry.get_config_data()` retrieves associated logs via `self.workoutlog_set.all()` with no user filter, the attacker's injected data is silently folded into the victim's progressive-overload calculations, corrupting their auto-generated weight and repetition targets. Version 2.6 contains a patch.

Affected: PyPI: wger

### Summary

An authenticated attacker can inject arbitrary workout log entries into any other user's `SlotEntry` by supplying the victim's `slot_entry` ID in a `POST /api/v2/workoutlog/` request. The `slot_entry` foreign key is not included in the ownership verification performed by `WorkoutLogViewSet.get_owner_objects()`, so the server accepts and persists the cross-user reference without error.

Because `SlotEntry.get_config_data()` retrieves associated logs via `self.workoutlog_set.all()` with **no user filter**, the attacker's injected data is silently folded into the victim's progressive-overload calculations, corrupting their auto-generated weight and repetition targets.

### Details

wger uses a centralized ownership-verification pattern in `WgerOwnerObjectModelViewSet.create()` (file: `wger/utils/viewsets.py`). This method iterates over the list returned by each ViewSet's `get_owner_objects()` and verifies that every listed foreign-key value in the request belongs to the authenticated user. **Foreign keys not present in the list are never checked.**

`WorkoutLogViewSet.get_owner_objects()` returns:

```python # File: wger/manager/api/views.py, lines 312-316 def get_owner_objects(self): return [(Routine, 'routine'), (WorkoutSession, 'session')] # ^^^^^^^ checked ^^^^^^^^^^^^^^^ checked # (SlotEntry, 'slot_entry') is MISSING ```

Because `slot_entry` is omitted, an attacker can supply their own `routine` (which passes the ownership check) alon…