Auth bypass in Open-Webui
CVE-2026-87994
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.
Vulnerability class: IDOR (Insecure Direct Object Reference)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N.
EPSS exploit prediction
EPSS: 0.004 (30.0th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 30th percentile — 30.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000
Affected products
- Open-Webui — versions >= 0.9.5, < 0.11.1
- Openwebui Open Webui
Weakness classification (CWE)
References
- github.com/open-webui/open-webui/security/advisories/GHSA-fmqh-xp37-5hr8 (Exploit, Vendor Advisory)
- github.com/open-webui/open-webui/pull/28631 (Patch, Issue Tracking)
- github.com/open-webui/open-webui/commit/7d392bedc9c1aaecc94509a58e59186b614433dc (Patch)
- github.com/open-webui/open-webui/releases/tag/v0.11.1 (Release Notes)
Frequently asked questions
- What is CVE-2026-87994?
- CVE-2026-87994 is a medium-severity vulnerability in Open-Webui, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 4.3/10. Published 2026-09-09.
- How severe is CVE-2026-87994?
- Medium severity. CVSS v3 base score is 4.3 out of 10.