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

Exploitation

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

CVSS

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

EPSS

• CVE-2026-87995: 0.42% estimated exploitation activity in the next 30 days; percentile 36.05 (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 shared terminal server could get script of their choosing to run in the Open WebUI origin itself. The in-app port preview rendered the content of a previewed port in an iframe whose sandbox always granted allow-same-origin alongside allow-scripts, and that content is served from a path on the application's own origin, so the sandbox provided no isolation at all. Script served on a previewed port 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 both the attacker and the victim. Deployments with no terminal server configured are not affected. - The attacker needs a normal authenticated account with access to that terminal connection, no admin rights, plus the ability to start a process listening on a port there. - Personal terminals a user configures for themselves are not affected. Those carry…

Published by the source

10 Sep 2026, 15:10 UTC

Last modified by the source

1 Oct 2026, 17:55 UTC

Source last checked

26 Oct 2026, 13:51 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-jmc6-2wr8-h3wj

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-jmc6-2wr8-h3wj

3. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-jmc6-2wr8-h3wj

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# Patch Next advisory brief: CVE-2026-87995

Advisory: Open WebUI: Same-origin XSS to account takeover via terminal port-preview iframe hardcoding allow-same-origin
IDs: CVE-2026-87995, GHSA-jmc6-2wr8-h3wj
Record: https://patchnext.com/advisories/cve-2026-87995 (revision 3, source checked 26 Oct 2026, 13:51 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: open-webui 0.11.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI open-webui: affected >= 0.8.11, <= 0.11.0; fixed in 0.11.1

## 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-jmc6-2wr8-h3wj (GitHub-reviewed advisory GHSA-jmc6-2wr8-h3wj lists affected ranges: PyPI open-webui >=0.8.11 <=0.11.0)
- Verified: https://osv.dev/vulnerability/GHSA-jmc6-2wr8-h3wj (OSV record GHSA-jmc6-2wr8-h3wj lists affected ranges: PyPI open-webui >=0.8.11 <0.11.1 (fixed))

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