Open WebUI: Authenticated users can target arbitrary configured Ollama backends via unguarded url_idx path parameter

Exploitation

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

CVSS

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

EPSS

• CVE-2026-54021: 0.28% estimated exploitation activity in the next 30 days; percentile 20.89 (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 Several direct, index-addressed Ollama proxy routes accept a caller-supplied urlidx path parameter and use it as a raw index into the admin-configured OLLAMABASEURLS list. Access control on these routes validates only whether the user may use the requested model, never which backend the request is routed to. Any authenticated user can append an arbitrary urlidx to force their request onto an Ollama backend they were never authorized to reach, including internal, higher-privilege, or explicitly admin-disabled backends. Affected endpoints All indexed Ollama routes that resolve the backend through getollamaurl(): Root cause backend/openwebui/routers/ollama.py — getollamaurl() consults the model-to-backend allow-list (OLLAMAMODELS[model]["urls"]) only when urlidx is omitted. When the caller supplies urlidx, that mapping is skipped and the value is used directly as an index: The outbound request is then sent to that backend using the backend's own configured API key. Backends an…

Published by the source

17 Jun 2026, 18:01 UTC

Last modified by the source

20 Jul 2026, 21:15 UTC

Source last checked

26 Oct 2026, 13:49 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-9rpj-v7hf-vv2w

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-9rpj-v7hf-vv2w

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# Patch Next advisory brief: CVE-2026-54021

Advisory: Open WebUI: Authenticated users can target arbitrary configured Ollama backends via unguarded url_idx path parameter
IDs: CVE-2026-54021, GHSA-9rpj-v7hf-vv2w
Record: https://patchnext.com/advisories/cve-2026-54021 (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: Medium (CVSS 6.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: open-webui 0.9.6. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI open-webui: affected <= 0.9.5; fixed in 0.9.6

## 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-9rpj-v7hf-vv2w (OSV record GHSA-9rpj-v7hf-vv2w lists affected ranges: PyPI open-webui >=0 <0.9.6 (fixed))
- Verified: https://github.com/advisories/GHSA-9rpj-v7hf-vv2w (GitHub-reviewed advisory GHSA-9rpj-v7hf-vv2w lists affected ranges: PyPI open-webui >=0 <=0.9.5)

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