Summary
Open WebUI: Stored web worker XSS via Pyodide
Title: Same-origin Pyodide code execution allows server-side RCE via a shared chat
Open 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.
Details
Pyodide'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.
from pyodide.http import pyfetch
import json
await pyfetch('/api/v1/functions/create', method='POST', credentials='include',
headers={'Content-Type': 'application/json'},
body=json.dumps({'id': 'x', 'name': 'x', 'meta': {'description': 'x'},
'content': "import os; os.system('<attacker command>')"}))
Patched
Pyodide 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.
Workaround
Until upgraded, disable Pyodide code execution or set the Code Execution / Code Interpreter engine to a server-side option.
Credits
@gg0h
Impact
When 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.
Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.
CVE-2026-59214 has a CVSS score of 7.3 (High). The vector is network-reachable, low privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.10.0); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2026-59214? CVE-2026-59214 is a high-severity cross-site scripting (XSS) vulnerability in open-webui (pip), affecting versions < 0.10.0. It is fixed in 0.10.0. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
- How severe is CVE-2026-59214? CVE-2026-59214 has a CVSS score of 7.3 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of open-webui are affected by CVE-2026-59214? open-webui (pip) versions < 0.10.0 is affected.
- Is there a fix for CVE-2026-59214? Yes. CVE-2026-59214 is fixed in 0.10.0. Upgrade to this version or later.
- Is CVE-2026-59214 exploitable, and should I be worried? Whether CVE-2026-59214 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-59214 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-59214? Upgrade
open-webuito 0.10.0 or later.