Open WebUI: Stored web worker XSS via Pyodide

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.3 · CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N

EPSS

• CVE-2026-59214: 0.42% estimated exploitation activity in the next 30 days; percentile 36.68 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Title: Same-origin Pyodide code execution allows server-side RCE via a shared chat Summary 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…

Published by the source

24 Jul 2026, 16:54 UTC

Last modified by the source

4 Aug 2026, 14:40 UTC

Source last checked

26 Oct 2026, 13:49 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-4r2p-27mh-5m22

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-4r2p-27mh-5m22

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# Patch Next advisory brief: CVE-2026-59214

Advisory: Open WebUI: Stored web worker XSS via Pyodide
IDs: CVE-2026-59214, GHSA-4r2p-27mh-5m22
Record: https://patchnext.com/advisories/cve-2026-59214 (revision 2, source checked 26 Oct 2026, 13:49 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: open-webui 0.10.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI open-webui: affected < 0.10.0; fixed in 0.10.0

## Suggested inspection (read-only)
- `python -m pip show open-webui`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on open-webui.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-4r2p-27mh-5m22 (OSV record GHSA-4r2p-27mh-5m22 lists affected ranges: PyPI open-webui >=0 <0.10.0 (fixed))
- Verified: https://github.com/advisories/GHSA-4r2p-27mh-5m22 (GitHub-reviewed advisory GHSA-4r2p-27mh-5m22 lists affected ranges: PyPI open-webui >=0 <0.10.0)

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