Open WebUI: Low-privilege authenticated users can enumerate and stop global background tasks, causing system-wide chat disruption

Exploitation

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

CVSS

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

EPSS

• CVE-2026-45399: 0.27% estimated exploitation activity in the next 30 days; percentile 19.22 (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 low privileges can enumerate active background tasks across the system and stop tasks belonging to other users via the GET /api/tasks and POST /api/tasks/stop/{taskid} methods. This allows a casual user to disrupt system-wide chat usage by continuously canceling other users' active tasks. This is a real authorization vulnerability affecting integrity and usability in multi-user deployments. Details Open WebUI exposes GET /api/tasks and POST /api/tasks/stop/{taskid} to any verified user. These endpoints operate on a global task namespace and accept raw taskid values without checking whether the task belongs to the current caller. As a result, a normal authenticated user can enumerate active global task IDs and stop tasks belonging to other users. Root cause: 1. Route authorization is too weak. In backend/openwebui/main.py, both endpoints only require getverifieduser: getverifieduser accepts both user and admin roles in…

Published by the source

14 May 2026, 20:26 UTC

Last modified by the source

13 Jul 2026, 16:43 UTC

Source last checked

26 Oct 2026, 13:41 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-8jjp-r2w2-4v22

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-8jjp-r2w2-4v22

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# Patch Next advisory brief: CVE-2026-45399

Advisory: Open WebUI: Low-privilege authenticated users can enumerate and stop global background tasks, causing system-wide chat disruption
IDs: CVE-2026-45399, GHSA-8jjp-r2w2-4v22
Record: https://patchnext.com/advisories/cve-2026-45399 (revision 2, source checked 26 Oct 2026, 13:41 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: open-webui 0.9.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI open-webui: affected <= 0.8.12; fixed in 0.9.0

## 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-8jjp-r2w2-4v22 (OSV record GHSA-8jjp-r2w2-4v22 lists affected ranges: PyPI open-webui >=0 <0.9.0 (fixed))
- Verified: https://github.com/advisories/GHSA-8jjp-r2w2-4v22 (GitHub-reviewed advisory GHSA-8jjp-r2w2-4v22 lists affected ranges: PyPI open-webui >=0 <=0.8.12)

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