Vulnerability · Published Sep 9, 2026 · Assigned by GitHub_M
CVE-2026-87994Open WebUI: Channel members can overwrite another member's message via the chat completions endpoint
Medium 4.3
In plain English
A medium-severity authorization bypass via user-controlled key in open-webui from open-webui. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 31% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| PyPI | open-webui | 0.11.1 | GHSA-fmqh-xp37-5hr8 |
| PyPI | open-webui | 0.11.1 | PYSEC-2026-4122 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| open-webui | open-webui | >= 0.9.5, < 0.11.1 |
Weakness: CWE-639, CWE-862 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
References
- https://github.com/open-webui/open-webui/security/advisories/GHSA-fmqh-xp37-5hr8 x_refsource_CONFIRM
- https://github.com/open-webui/open-webui/pull/28631 x_refsource_MISC
- https://github.com/open-webui/open-webui/commit/7d392bedc9c1aaecc94509a58e59186b614433dc x_refsource_MISC
- https://github.com/open-webui/open-webui/releases/tag/v0.11.1 x_refsource_MISC