Open WebUI: Mass Assignment via FeedbackForm extra=allow Allows Feedback User ID Spoofing and Evaluation Data Manipulation

Exploitation

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

CVSS

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

EPSS

• CVE-2026-45396: 0.31% estimated exploitation activity in the next 30 days; percentile 23.56 (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.

Mass Assignment in Feedback Creation Allows User ID Spoofing and Evaluation Data Manipulation Summary The POST /api/v1/evaluations/feedback endpoint in Open WebUI v0.9.2 is vulnerable to mass assignment via FeedbackForm, which uses modelconfig = ConfigDict(extra='allow'). Due to an insecure dictionary merge order in insertnewfeedback(), an authenticated attacker can inject a userid field in the request body that overwrites the server-derived value, creating feedback records attributed to any arbitrary user. This corrupts the model evaluation leaderboard (Elo ratings) and enables identity spoofing. Details The vulnerability exists in two layers: 1. Model Layer — Insecure Dict Merge Order File: backend/openwebui/models/feedbacks.py, lines 148–160 In Python, when a dictionary literal contains duplicate keys, the last value wins. Since formdata.modeldump() appears after 'userid': userid, any userid field in the form data overwrites the authenticated user's ID. 2. Schema Layer —…

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-rjmp-vjf2-qf4g

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-rjmp-vjf2-qf4g

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# Patch Next advisory brief: CVE-2026-45396

Advisory: Open WebUI: Mass Assignment via FeedbackForm extra=allow Allows Feedback User ID Spoofing and Evaluation Data Manipulation
IDs: CVE-2026-45396, GHSA-rjmp-vjf2-qf4g
Record: https://patchnext.com/advisories/cve-2026-45396 (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: Medium (CVSS 5.4)
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 < 0.9.5; 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-rjmp-vjf2-qf4g (OSV record GHSA-rjmp-vjf2-qf4g lists affected ranges: PyPI open-webui >=0 <0.9.5 (fixed))
- Verified: https://github.com/advisories/GHSA-rjmp-vjf2-qf4g (GitHub-reviewed advisory GHSA-rjmp-vjf2-qf4g lists affected ranges: PyPI open-webui >=0 <0.9.5)

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