Open WebUI: Channel members can overwrite another member's message via the chat completions endpoint

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-87994
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-09 22:18:47 UTC
Updated2026-09-09 22:18:47 UTC
DescriptionOpen WebUI is an extensible, feature-rich, and user-friendly self-hosted AI platform. From 0.9.5 until 0.11.1, the channel branch of chat_completion in backend/open_webui/main.py checked channel write access and channel membership for a supplied message_id but did not verify that the calling user authored the targeted message. A channel member could use the chat completions endpoint to replace another member's message while preserving the victim as the stored author, altering the conversation record without gaining access to other channels. This issue is fixed in version 0.11.1.

Risk And Classification

Primary CVSS: v3.1 4.3 MEDIUM from [email protected]

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

Problem Types: CWE-639 | CWE-862 | CWE-639 CWE-639: Authorization Bypass Through User-Controlled Key | CWE-862 CWE-862: Missing Authorization

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary4.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
3.1CNADECLARED4.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Open-webui Open-webui affected >= 0.9.5, < 0.11.1 Not specified

References

ReferenceSourceLinkTags
github.com/open-webui/open-webui/pull/28631 [email protected] github.com
github.com/open-webui/open-webui/commit/7d392bedc9c1aaecc94509a58e59186b... [email protected] github.com
github.com/open-webui/open-webui/security/advisories/GHSA-fmqh-xp37-5hr8 [email protected] github.com
github.com/open-webui/open-webui/releases/tag/v0.11.1 [email protected] github.com
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