CVE-2026-45396

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

State: Published
Severity: 5.4 Medium
Published: May 15, 2026
Updated: May 15, 2026
Reserved: May 12, 2026

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Description

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.

Scores

CVSS	Score	Vector	Source
3.1	5.4 Medium	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L	GitHub_M

Weaknesses

CWE-915 Improperly Controlled Modification of Dynamically-Determined Object Attributes

Affected Products

Product	Versions
open-webuiopen-webui	< 0.9.5Affected

References

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

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