CVE-2026-45396

MEDIUM 5.4

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

CVSS Score

5.4

EPSS Score

0.0%

EPSS Percentile

0th

Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.5, the POST /api/v1/evaluations/feedback endpoint in Open WebUI v0.9.2 is vulnerable to mass assignment via FeedbackForm, which uses model_config = ConfigDict(extra='allow'). Due to an insecure dictionary merge order in insert_new_feedback(), an authenticated attacker can inject a user_id 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. This vulnerability is fixed in 0.9.5.

CWE	CWE-915
Vendor	open-webui
Product	open-webui
Published	May 15, 2026
Last Updated	May 15, 2026

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CVSS v3 Breakdown

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

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

Low

Availability

Low

Affected Versions

open-webui / open-webui

< 0.9.5

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/open-webui/open-webui/security/advisories/GHSA-rjmp-vjf2-qf4g