CVE-2026-87994
Open WebUI: Channel members can overwrite another member's message via the chat completions endpoint
CVSS Score
4.3
EPSS Score
0.0%
EPSS Percentile
0th
Open 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.
| CWE | CWE-639 CWE-862 |
| Vendor | open-webui |
| Product | open-webui |
| Published | Sep 9, 2026 |
| Last Updated | Sep 10, 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:N Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None
Affected Versions
open-webui / open-webui
>= 0.9.5, < 0.11.1
References
github.com: https://github.com/open-webui/open-webui/security/advisories/GHSA-fmqh-xp37-5hr8 github.com: https://github.com/open-webui/open-webui/pull/28631 github.com: https://github.com/open-webui/open-webui/commit/7d392bedc9c1aaecc94509a58e59186b614433dc github.com: https://github.com/open-webui/open-webui/releases/tag/v0.11.1