{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 0.9.5"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "open-webui"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.9.6"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-54021"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-863"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-17T18:01:50Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "## Summary\n\nSeveral direct, index-addressed Ollama proxy routes accept a caller-supplied `url_idx`\npath parameter and use it as a raw index into the admin-configured `OLLAMA_BASE_URLS`\nlist. Access control on these routes validates only whether the user may use the\nrequested *model*, never which *backend* the request is routed to. Any authenticated\nuser can append an arbitrary `url_idx` to force their request onto an Ollama backend\nthey were never authorized to reach, including internal, higher-privilege, or\nexplicitly admin-disabled backends.\n\n## Affected endpoints\n\nAll indexed Ollama routes that resolve the backend through `get_ollama_url()`:\n\n```\nPOST /ollama/api/chat/{url_idx}\nPOST /ollama/api/generate/{url_idx}\nPOST /ollama/api/embed/{url_idx}\nPOST /ollama/api/embeddings/{url_idx}\nPOST /ollama/v1/chat/completions/{url_idx}\nPOST /ollama/v1/completions/{url_idx}\nPOST /ollama/v1/messages/{url_idx}\nPOST /ollama/v1/responses/{url_idx}\n```\n\n## Root cause\n\n`backend/open_webui/routers/ollama.py` \u2014 `get_ollama_url()` consults the\nmodel-to-backend allow-list (`OLLAMA_MODELS[model][\"urls\"]`) only when `url_idx` is\nomitted. When the caller supplies `url_idx`, that mapping is skipped and the value is\nused directly as an index:\n\n```python\nasync def get_ollama_url(request: Request, model: str, url_idx: Optional[int] = None):\n    if url_idx is None:\n        models = request.app.state.OLLAMA_MODELS\n        if model not in models:\n            raise HTTPException(...)\n        url_idx = random.choice(models[model].get(\"urls\", []))\n    url = request.app.state.config.OLLAMA_BASE_URLS[url_idx]   # caller-controlled, no authz\n    return url, url_idx\n```\n\nThe outbound request is then sent to that backend using the backend\u0027s own configured\nAPI key. Backends an admin has disabled (`OLLAMA_API_CONFIGS[\"\u003cidx\u003e\"].enable = false`)\nare hidden from model discovery but remain reachable through the indexed route, because\nthe disabled state is never re-checked at request time.\n\n## Impact\n\nA verified, non-admin user with read access to any single model can:\n- route requests to internal / higher-capability / restricted Ollama backends in\n  multi-backend deployments, bypassing backend-level isolation;\n- reach backends the admin has explicitly disabled;\n- have those requests authenticated with the target backend\u0027s configured API key\n  (the key is used server-side; it is not returned to the attacker);\n- consume the restricted backend\u0027s compute.\n\nThere is no cross-user data disclosure and no exfiltration of the backend credential\nitself; the impact is unauthorized access to, and use of, restricted backend resources.\n\n## Affected / Patched\n\n- Affected: `\u003c= 0.9.5`\n- Patched: `\u003e= 0.9.6`\n\n## Fix\n\n0.9.6 adds `validate_ollama_backend_idx()`, invoked on every indexed route (directly and\nvia `get_ollama_url()`), which returns 403 for any non-admin caller-supplied `url_idx`\nthat is not in the requested model\u0027s allowed `urls`. Because disabled backends are absent\nfrom every model\u0027s `urls`, the same check also blocks routing to disabled backends.",
  "id": "GHSA-9rpj-v7hf-vv2w",
  "modified": "2026-06-17T18:01:50Z",
  "published": "2026-06-17T18:01:50Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/open-webui/open-webui/security/advisories/GHSA-9rpj-v7hf-vv2w"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/open-webui/open-webui"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Open WebUI: Authenticated users can target arbitrary configured Ollama backends via unguarded url_idx path parameter"
}