{"id":"PYSEC-2026-3590","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('\u003cattacker command\u003e')\"}))\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","aliases":["CVE-2026-59214","GHSA-4r2p-27mh-5m22"],"modified":"2026-08-04T14:30:17.752429795Z","published":"2026-08-04T11:34:42.338553Z","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"},{"type":"PACKAGE","url":"https://pypi.org/project/open-webui"},{"type":"ADVISORY","url":"https://github.com/advisories/GHSA-4r2p-27mh-5m22"}],"affected":[{"package":{"name":"open-webui","ecosystem":"PyPI","purl":"pkg:pypi/open-webui"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.10.0"}]}],"versions":["0.1.124","0.1.125","0.2.0","0.2.1","0.2.2","0.2.3","0.2.4","0.2.5","0.3.0","0.3.1","0.3.10","0.3.12","0.3.13","0.3.14","0.3.15","0.3.16","0.3.17","0.3.17.dev2","0.3.17.dev3","0.3.17.dev4","0.3.17.dev5","0.3.18","0.3.19","0.3.2","0.3.20","0.3.21","0.3.22","0.3.23","0.3.24","0.3.25","0.3.26","0.3.27","0.3.27.dev1","0.3.27.dev2","0.3.27.dev3","0.3.28","0.3.29","0.3.3","0.3.30","0.3.30.dev1","0.3.30.dev2","0.3.31","0.3.31.dev1","0.3.32","0.3.33","0.3.33.dev1","0.3.34","0.3.35","0.3.4","0.3.5","0.3.6","0.3.7","0.3.8","0.3.9","0.4.0","0.4.0.dev1","0.4.0.dev2","0.4.1","0.4.2","0.4.3","0.4.4","0.4.5","0.4.6","0.4.6.dev1","0.4.7","0.4.8","0.5.0","0.5.0.dev1","0.5.0.dev2","0.5.1","0.5.10","0.5.11","0.5.12","0.5.13","0.5.14","0.5.15","0.5.16","0.5.17","0.5.18","0.5.19","0.5.2","0.5.20","0.5.3","0.5.3.dev1","0.5.4","0.5.5","0.5.6","0.5.7","0.5.8","0.5.9","0.6.0","0.6.1","0.6.10","0.6.11","0.6.12","0.6.13","0.6.14","0.6.15","0.6.16","0.6.18","0.6.19","0.6.2","0.6.20","0.6.21","0.6.22","0.6.23","0.6.24","0.6.25","0.6.26","0.6.26.dev1","0.6.27","0.6.28","0.6.29","0.6.3","0.6.30","0.6.31","0.6.32","0.6.33","0.6.34","0.6.35","0.6.36","0.6.37","0.6.38","0.6.39","0.6.4","0.6.40","0.6.41","0.6.42","0.6.43","0.6.5","0.6.6","0.6.6.dev1","0.6.7","0.6.8","0.6.9","0.7.0","0.7.1","0.7.2","0.8.0","0.8.1","0.8.10","0.8.11","0.8.12","0.8.2","0.8.3","0.8.4","0.8.5","0.8.6","0.8.7","0.8.8","0.8.9","0.9.0","0.9.1","0.9.2","0.9.3","0.9.4","0.9.5","0.9.6"],"database_specific":{"source":"https://github.com/pypa/advisory-database/blob/main/vulns/open-webui/PYSEC-2026-3590.yaml"}}],"schema_version":"1.8.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N"}]}