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High, CVSS 7.5amended

Open WebUI: Unauthenticated requests can stall the server via uncached OIDC fetches in back-channel logout

CVE-2026-87011GHSA-3g9q-v48f-hh9w

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (open-webui 0.11.1), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • PyPI open-webui

    Affected
    >= 0.9.0, <= 0.11.0
    Fixed in
    0.11.1

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS
  • CVE-2026-87011: 0.64% estimated exploitation activity in the next 30 days; percentile 50.92 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary The OIDC back-channel logout endpoint is unauthenticated by design, because the identity provider calls it without a browser session. Before checking whether the submitted logout token was genuine, the handler fetched the provider's discovery document and its signing keys over the network, and repeated both fetches on every request because nothing was cached. The signing-key fetch also ran as a blocking call inside the async event loop. A small number of requests carrying a worthless token was therefore enough to make the whole instance stop answering. Preconditions - ENABLEOAUTHBACKCHANNELLOGOUT=true. The default is False, so a stock deployment is not affected. This setting is recommended in the Open WebUI hardening documentation, which is why the issue is treated as in scope. - At least one OIDC provider configured (OAUTHCLIENTID, OAUTHCLIENTSECRET, OPENIDPROVIDERURL). - No account, credential, session or secret identifier is required. The attacker needs network access to…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 3 · amended ·

    Amended from ghsa record GHSA-3g9q-v48f-hh9w

  2. Revision 2 · amended ·

    Amended from osv record GHSA-3g9q-v48f-hh9w

  3. Revision 1 · created ·

    Published from ghsa record GHSA-3g9q-v48f-hh9w

Agent brief

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# Patch Next advisory brief: CVE-2026-87011

Advisory: Open WebUI: Unauthenticated requests can stall the server via uncached OIDC fetches in back-channel logout
IDs: CVE-2026-87011, GHSA-3g9q-v48f-hh9w
Record: https://patchnext.com/advisories/cve-2026-87011 (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 7.5)
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 >= 0.9.0, <= 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-3g9q-v48f-hh9w (GitHub-reviewed advisory GHSA-3g9q-v48f-hh9w lists affected ranges: PyPI open-webui >=0.9.0 <=0.11.0)
- Verified: https://osv.dev/vulnerability/GHSA-3g9q-v48f-hh9w (OSV record GHSA-3g9q-v48f-hh9w lists affected ranges: PyPI open-webui >=0.9.0 <0.11.1 (fixed))

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