{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "wger"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "2.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-27838"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-639"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-02-26T22:15:30Z",
    "nvd_published_at": "2026-02-26T23:16:34Z",
    "severity": "LOW"
  },
  "details": "### Summary\n\nFive routine detail action endpoints check a cache before calling `self.get_object()`. Cache keys are scoped only by `pk` \u2014 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.\n\n### Details\n\n`wger/manager/api/views.py` \u2014 five actions follow this pattern (lines 134\u2013201):\n\n```python\n@action(detail=True)\ndef date_sequence_display_mode(self, request, pk=None):\n    cache_key = make_routine_api_date_sequence_display_cache_key(pk)\n    cached = cache.get(cache_key)\n    if cached:\n        return Response(cached)   # returned WITHOUT calling self.get_object()\n    # only reaches ownership check on cache miss\n    routine = self.get_object()\n    ...\n```\n\nCache key construction in `wger/utils/cache.py:89\u2013106`:\n\n```python\ndef make_routine_api_date_sequence_display_cache_key(routine_id):\n    return f\"routine-api-date-sequence-display-{routine_id}\"\n    # No user ID in key\n```\n\nCache TTL: 1 month (`4 * 604800` seconds, `settings_global.py:461`).\n\nAffected endpoints:\n```\nGET /api/v2/routine/{pk}/date-sequence-display/\nGET /api/v2/routine/{pk}/date-sequence-gym/\nGET /api/v2/routine/{pk}/structure/\nGET /api/v2/routine/{pk}/logs/\nGET /api/v2/routine/{pk}/stats/\n```\n\n### PoC\n\n```\n1. Victim (user A) visits GET /api/v2/routine/5/structure/ \u2192 response cached under key \"routine-api-structure-5\"\n2. Attacker (user B) visits GET /api/v2/routine/5/structure/ \u2192 cache hit \u2192 returns user A\u0027s routine structure without any ownership check\n```\n\nRequires the victim to have previously accessed the endpoint (cache must be populated). Once populated, the cache entry is valid for 1 month.\n\n### Impact\n\nAn attacker with a registered account can retrieve another user\u0027s routine details \u2014 workout day sequences, exercise structure, training logs, and statistics \u2014 from cache without ownership verification.\n\n**Fix**: Include the user ID in the cache key:\n```python\ndef make_routine_api_date_sequence_display_cache_key(routine_id, user_id):\n    return f\"routine-api-date-sequence-display-{user_id}-{routine_id}\"\n```\n\nOr move `self.get_object()` before the cache lookup so ownership is always verified first.",
  "id": "GHSA-42cr-w2gr-m54q",
  "modified": "2026-02-27T21:59:39Z",
  "published": "2026-02-26T22:15:30Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/wger-project/wger/security/advisories/GHSA-42cr-w2gr-m54q"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-27838"
    },
    {
      "type": "WEB",
      "url": "https://github.com/wger-project/wger/commit/e964328784e2ee2830a1991d69fadbce86ac9fbf"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/wger-project/wger"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "wger: IDOR via user-unscoped cache keys on routine API actions exposes workout data"
}