CVE-2026-59214: Open WebUI Cross-Site Scripting Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-4r2p-27mh-5m22",
  "modified" : "2026-07-24T16:54:40Z",
  "published" : "2026-07-24T16:54:40Z",
  "aliases" : [ "CVE-2026-59214" ],
  "summary" : "Open WebUI: Stored web worker XSS via Pyodide",
  "details" : "**Title:** Same-origin Pyodide code execution allows server-side RCE via a shared chat\n\n### Summary\n\nOpen WebUI runs client-side Python (Pyodide) in a same-origin web worker. Through Pyodide's JavaScript API (`pyodide.http.pyfetch`, or the `js` module which exposes the page's `fetch` / `XMLHttpRequest`) executed Python can issue requests on the application origin, and those requests carry the victim's session cookie. A low-privileged user can store such a payload in a chat message, share the chat, and when a victim opens it and clicks **Run** the payload executes authenticated same-origin requests as the victim. When the victim is an admin (or a user holding `workspace.functions` / `workspace.tools` permissions) the payload creates a Function/Tool whose body runs server-side, yielding **remote code execution**.\n\n### Details\n\nPyodide's `js` bridge gives Python in the worker the same reach as inline JavaScript on the origin, and the worker is same-origin, so a credentialed request to the app's own API is authenticated as the victim. No separate XSS sink is required: storing the payload in a shared chat and having the victim run it is enough.\n\n```python\nfrom pyodide.http import pyfetch\nimport json\nawait pyfetch('/api/v1/functions/create', method='POST', credentials='include',\n              headers={'Content-Type': 'application/json'},\n              body=json.dumps({'id': 'x', 'name': 'x', 'meta': {'description': 'x'},\n                               'content': \"import os; os.system('<attacker command>')\"}))\n```\n\n### Impact\n\nWhen the victim runs the shared code, an authenticated low-privileged user achieves remote code execution on the server (the created Function/Tool runs server-side Python) if the victim is an admin or holds `workspace.functions` / `workspace.tools` permissions. More generally the executed code can issue any authenticated request as the victim. Requires the victim to click Run, and Open WebUI configured to use Pyodide.\n\n### Patched\n\nPyodide now runs in a sandboxed iframe at an opaque origin by default (`sandbox=\"allow-scripts\"`, no `allow-same-origin`). At an opaque origin `pyfetch`, `fetch` and `XMLHttpRequest` to the app become cross-origin requests that carry no session cookie and are CORS-blocked, and the `js` bridge operates on the isolated iframe window with no access to the parent's cookie, token, `localStorage` or DOM. Full Python, JavaScript and external fetch keep working. IDBFS persistence is available only behind `ENABLE_PYODIDE_FILE_PERSISTENCE=true`, which restores the same-origin worker and re-accepts this risk.\n\n### Workaround\n\nUntil upgraded, disable Pyodide code execution or set the Code Execution / Code Interpreter engine to a server-side option.\n\n### Credits\n\n@gg0h",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "open-webui"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.10.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/open-webui/open-webui/security/advisories/GHSA-4r2p-27mh-5m22"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-59214"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/open-webui/open-webui"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-24T16:54:40Z",
    "nvd_published_at" : "2026-07-09T17:17:02Z"
  }
}