{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "cpe": "cpe:2.3:a:openwebui:open_webui:*:*:*:*:*:*:*:*",
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "0.9.0"
              }
            ],
            "source": [
              "AFFECTED_FIELD",
              "CPE_RANGE"
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "f31768e20e5c6b4f6da0ef657877298b359936cf"
            }
          ],
          "repo": "https://github.com/open-webui/open-webui",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-9vvh-qmjx-p4q8"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-862"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/44xxx/CVE-2026-44555.json"
  },
  "details": "Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.0, Open WebUI supports model composition via base_model_id: a user-defined model (e.g., \"Cheap Assistant\") can reference an existing base model (e.g., \"gpt-4-turbo-restricted\") that provides the actual inference capability. When a user queries the composed model, the access control pipeline verifies the user has access to the composed model but never re-verifies access to the chained base model. Additionally, the model creation and import endpoints accept arbitrary base_model_id values without checking that the caller has access to that base model. Combined, this allows any user with the default model creation permission to create a model that chains to a restricted base model — and then invoke it, causing the server to dispatch the request to the restricted base model using the admin-configured API key. This vulnerability is fixed in 0.9.0.",
  "id": "CVE-2026-44555",
  "modified": "2026-07-08T05:37:20.797095678Z",
  "published": "2026-05-15T19:48:35.352Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/44xxx/CVE-2026-44555.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/open-webui/open-webui/security/advisories/GHSA-9vvh-qmjx-p4q8"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-44555"
    }
  ],
  "schema_version": "1.7.5",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Open WebUI: Base Model Routing Bypasses Access Control via Model Chaining"
}