CVE-2026-45349: Open WebUI: Broken Access Control for Completions API

Severity: high (CVSS 7.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-05-15 · updated 2026-06-17
Weakness: CWE-639

Description

Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.0, a user just needs to use the API endpoint: /api/chat/completions with their own API key (generated in OWUI) and the Chat ID of another user to continue the conversation of the other user. This vulnerability is fixed in 0.9.0.

Affected products

open-webui: before 0.9.0 — fixed in 0.9.0

How to fix

Upgrade to a fixed version: open-webui 0.9.0. Check the vendor advisory for mitigations.

References

https://github.com/open-webui/open-webui/security/advisories/GHSA-gfm2-xm6c-37qc
https://github.com/open-webui/open-webui/security/advisories/GHSA-gfm2-xm6c-37qc

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