---
id: CVE-2026-27838
aliases:
  - GHSA-42cr-w2gr-m54q
  - PYSEC-2026-3418
title: >-
  wger: IDOR via user-unscoped cache keys on routine API actions exposes workout
  data
summary: >-
  wger: IDOR via user-unscoped cache keys on routine API actions exposes workout
  data
severity: low
cvss: 3.1
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N'
vendor: wger
product: wger
ecosystem: pip
affected:
  - wger <= 2.1
published: '2026-02-26'
updated: '2026-07-13'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-42cr-w2gr-m54q'
references:
  - url: >-
      https://github.com/wger-project/wger/security/advisories/GHSA-42cr-w2gr-m54q
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-27838'
  - url: >-
      https://github.com/wger-project/wger/commit/e964328784e2ee2830a1991d69fadbce86ac9fbf
  - url: 'https://github.com/wger-project/wger'
tags:
  - osv
  - pip
epss: 0.00251
epssPercentile: 0.14681
ingestedAt: '2026-07-13T18:57:52.231Z'
---

## Overview

### Summary

Five routine detail action endpoints check a cache before calling `self.get_object()`. Cache keys are scoped only by `pk` — no user ID is included. When a victim has previously accessed their routine via the API, an attacker can retrieve the cached response for the same PK without any ownership check.

### Details

`wger/manager/api/views.py` — five actions follow this pattern (lines 134–201):

```python
@action(detail=True)
def date_sequence_display_mode(self, request, pk=None):
    cache_key = make_routine_api_date_sequence_display_cache_key(pk)
    cached = cache.get(cache_key)
    if cached:
        return Response(cached)   # returned WITHOUT calling self.get_object()
    # only reaches ownership check on cache miss
    routine = self.get_object()
    ...
```

Cache key construction in `wger/utils/cache.py:89–106`:

```python
def make_routine_api_date_sequence_display_cache_key(routine_id):
    return f"routine-api-date-sequence-display-{routine_id}"
    # No user ID in key
```

Cache TTL: 1 month (`4 * 604800` seconds, `settings_global.py:461`).

Affected endpoints:
```
GET /api/v2/routine/{pk}/date-sequence-display/
GET /api/v2/routine/{pk}/date-sequence-gym/
GET /api/v2/routine/{pk}/structure/
GET /api/v2/routine/{pk}/logs/
GET /api/v2/routine/{pk}/stats/
```

### PoC

```
1. Victim (user A) visits GET /api/v2/routine/5/structure/ → response cached under key "routine-api-structure-5"
2. Attacker (user B) visits GET /api/v2/routine/5/structure/ → cache hit → returns user A's routine structure without any ownership check
```

Requires the victim to have previously accessed the endpoint (cache must be populated). Once populated, the cache entry is valid for 1 month.

### Impact

An attacker with a registered account can retrieve another user's routine details — workout day sequences, exercise structure, training logs, and statistics — from cache without ownership verification.

**Fix**: Include the user ID in the cache key:
```python
def make_routine_api_date_sequence_display_cache_key(routine_id, user_id):
    return f"routine-api-date-sequence-display-{user_id}-{routine_id}"
```

Or move `self.get_object()` before the cache lookup so ownership is always verified first.

## Affected packages

- `wger <= 2.1`

## Remediation

Refer to the advisory for the patched release.