CVE-2026-45339CWE-863

Open WebUI: API key endpoint restrictions bypassed via `x-api-key` header — full message processing on restricted endpoints

Medium · published May 15, 2026

CVSS v3.1
6.5
EPSS
0%
Percentile
37.1
In the wild
Unconfirmed
What it is

Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.0, Open WebUI allows admins to restrict which API endpoints an API key can access. When an API key is restricted from /api/v1/messages, requests using the Authorization: Bearer sk-... header are correctly blocked with 403. However, the same key sent via the x-api-key header bypasses the restriction entirely — the request is authenticated, the model is invoked, and a full response is returned. This vulnerability is fixed in 0.9.0.

The record
Technical detail
CVSS v3.1
6.5 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N
CVSS v4.0
Not supplied
EPSS
0.00438 · 37.1th percentile
Weakness
CWE-863 · Incorrect Authorization
Published
2026-05-15T19:21Z
EPSS history
Timeline
  • 15 MAY 19:21Z
    Open WebUI: API key endpoint restrictions bypassed via `x-api-key` header — full message processing on restricted endpoints
    cvelistv5