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Medium, CVSS 6.5amended

Open WebUI: Cross-user file disclosure via /api/chat/completions image_url field

CVE-2026-54009GHSA-wch8-mhj5-9frg

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (open-webui 0.9.6), 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

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
6.5 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
EPSS
  • CVE-2026-54009: 0.38% estimated exploitation activity in the next 30 days; percentile 32.34 (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 POST /api/chat/completions accepts an imageurl.url value that, when it does NOT start with http://, https://, or data:image/, is interpreted as a file id and resolved against the global file table with no ownership check. An authenticated user can therefore set imageurl.url to another user's file id, the server reads that file from disk, base64-encodes it, and injects the data URI into the LLM request. The user then prompts the LLM to describe / OCR the file and reads the content back. Same class as CVE-2026-44560 (RAG cross-user access) and the multiple hasaccesstofile checks added in routers/files.py -- the auth boundary was tightened on the file router but not on this conversion path. affected code backend/openwebui/utils/middleware.py:2113-2150 -- converturlimagestobase64: called from the main chat completion middleware at middleware.py:2357: backend/openwebui/utils/files.py:57-95 -- getimagebase64fromurl: Files.getfilebyid in models/files.py:161 does a bare db.get(File,…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from ghsa record GHSA-wch8-mhj5-9frg

  2. Revision 1 · created ·

    Published from osv record GHSA-wch8-mhj5-9frg

Agent brief

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# Patch Next advisory brief: CVE-2026-54009

Advisory: Open WebUI: Cross-user file disclosure via /api/chat/completions image_url field
IDs: CVE-2026-54009, GHSA-wch8-mhj5-9frg
Record: https://patchnext.com/advisories/cve-2026-54009 (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 6.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: open-webui 0.9.6. 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-wch8-mhj5-9frg (OSV record GHSA-wch8-mhj5-9frg lists affected ranges: PyPI open-webui >=0 <0.9.6 (fixed))
- Verified: https://github.com/advisories/GHSA-wch8-mhj5-9frg (GitHub-reviewed advisory GHSA-wch8-mhj5-9frg lists affected ranges: PyPI open-webui >=0 <=0.9.5)

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