Open WebUI: Cross-User File Access via Unchecked file_id in Folder Knowledge and Knowledge-Base Attach Endpoints

Exploitation

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

CVSS

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

EPSS

• CVE-2026-45402: 0.35% estimated exploitation activity in the next 30 days; percentile 28.23 (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.

Cross-User File Access via Unchecked fileid in Folder Knowledge and Knowledge-Base Attach Endpoints Summary Multiple endpoints accept a user-supplied fileid and attach the referenced file to a resource the caller controls (folder knowledge, knowledge-base contents) without verifying that the caller owns or has been granted access to the file. The file's content then becomes reachable through the downstream RAG / file-content paths, allowing any authenticated user to exfiltrate any other user's private file — and on the knowledge-base path, also to overwrite it — given knowledge of the file's UUID. Affected code paths Path 1 — Folder knowledge ingestion via folders.update backend/openwebui/routers/folders.py:156 — POST /api/v1/folders/{id}/update accepts a FolderUpdateForm whose data: Optional[dict] field is written verbatim into the folder. The folder consumer at backend/openwebui/utils/middleware.py:2409 spreads folder.data['files'] directly into formdata['files'] for the next chat…

Published by the source

14 May 2026, 20:27 UTC

Last modified by the source

13 Jul 2026, 16:42 UTC

Source last checked

26 Oct 2026, 13:41 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-r472-mw7m-967f

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-r472-mw7m-967f

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# Patch Next advisory brief: CVE-2026-45402

Advisory: Open WebUI: Cross-User File Access via Unchecked file_id in Folder Knowledge and Knowledge-Base Attach Endpoints
IDs: CVE-2026-45402, GHSA-r472-mw7m-967f
Record: https://patchnext.com/advisories/cve-2026-45402 (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 8.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: open-webui 0.9.5. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI open-webui: affected <= 0.9.4; fixed in 0.9.5

## 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-r472-mw7m-967f (OSV record GHSA-r472-mw7m-967f lists affected ranges: PyPI open-webui >=0 <0.9.5 (fixed))
- Verified: https://github.com/advisories/GHSA-r472-mw7m-967f (GitHub-reviewed advisory GHSA-r472-mw7m-967f lists affected ranges: PyPI open-webui >=0 <=0.9.4)

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