Open WebUI: Same-origin XSS to account takeover via terminal file-preview iframe hardcoding allow-same-origin

Exploitation

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

CVSS

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

EPSS

• CVE-2026-70486: 0.38% estimated exploitation activity in the next 30 days; percentile 32.01 (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.

Summary Any authenticated user with access to a terminal server could get script of their choosing to run in the Open WebUI origin itself. The HTML file preview rendered terminal-served files in an iframe whose sandbox always granted allow-same-origin alongside allow-scripts, and the file is served from a path on the application's own origin, so the sandbox provided no isolation at all. Script in a previewed file could read the victim's session token and take over the account. Preconditions - At least one terminal server configured by an admin (TERMINALSERVERCONNECTIONS, empty by default) and reachable by the victim. Deployments with no terminal server configured are not affected. - The attacker needs a normal authenticated account with access to that terminal server, no admin rights. - No victim interaction beyond having the chat open: a displayfile tool call opens the preview automatically. - TERMINALPROXYHEADERS unset, which is the default. An operator who had already set a…

Published by the source

4 Aug 2026, 20:02 UTC

Last modified by the source

4 Aug 2026, 20:02 UTC

Source last checked

26 Oct 2026, 13:50 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-3xpf-xq7r-v8c5

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# Patch Next advisory brief: CVE-2026-70486

Advisory: Open WebUI: Same-origin XSS to account takeover via terminal file-preview iframe hardcoding allow-same-origin
IDs: CVE-2026-70486, GHSA-3xpf-xq7r-v8c5
Record: https://patchnext.com/advisories/cve-2026-70486 (revision 1, source checked 26 Oct 2026, 13:50 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.2)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: open-webui 0.11.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI open-webui: affected >= 0.9.0, <= 0.10.2; fixed in 0.11.0

## 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://github.com/advisories/GHSA-3xpf-xq7r-v8c5 (GitHub-reviewed advisory GHSA-3xpf-xq7r-v8c5 lists affected ranges: PyPI open-webui >=0.9.0 <=0.10.2)

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