CVE-2026-87994CWE-639CWE-862broken-access-control

CVE-2026-87994

Medium · published September 10, 2026

CVSS v3.1
4.3
EPSS
0%
Percentile
29.9
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
4.3 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
CVSS v4.0
Not supplied
EPSS
0.00372 · 29.9th percentile
Weaknesses
CWE-639 · Authorization Bypass Through User-Controlled Key; CWE-862 · Missing Authorization
Published
2026-09-10T02:18Z
Affected products (1)
ProductVersionsFixed in
openwebui/open_webui≥ 0.9.5, < 0.11.10.11.1
References (5)
https://github.com/open-webui/open-webui/commit/7d392bedc9c1aaecc94509a58e59186b614433dc · [email protected]https://github.com/open-webui/open-webui/pull/28631 · [email protected]https://github.com/open-webui/open-webui/releases/tag/v0.11.1 · [email protected]https://github.com/open-webui/open-webui/security/advisories/GHSA-fmqh-xp37-5hr8 · [email protected]https://github.com/open-webui/open-webui/security/advisories/GHSA-fmqh-xp37-5hr8 · 134c704f-9b21-4f2e-91b3-4a467353bcc0
EPSS history
Timeline
  • 11 SEP 03:19Z
    EPSS moved — → 0%
    epss
  • 09 SEP 21:24Z
    Open WebUI: Channel members can overwrite another member's message via the chat completions endpoint
    cvelistv5