CVE-2026-54021: open-webui Incorrect Authorization

Vulnerability summary

CVE-2026-54021 is a medium (CVSS 6.3) Incorrect Authorization vulnerability in open-webui. EPSS estimates a 0.28% chance of exploitation in the next 30 days, higher than 19.5% of scored vulnerabilities.

Timeline

1. 23-06-2026
   PublishedVulnerability first disclosed.
2. 26-06-2026
   Last modifiedVulnerability information updated.

Description

Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.6, several direct, index-addressed Ollama proxy routes accept a caller-supplied url_idx path parameter and use it as a raw index into the admin-configured OLLAMA_BASE_URLS list. Access control on these routes validates only whether the user may use the requested model, never which backend the request is routed to. Any authenticated user can append an arbitrary url_idx to force their request onto an Ollama backend they were never authorized to reach, including internal, higher-privilege, or explicitly admin-disabled backends. This vulnerability is fixed in 0.9.6.

• CWE-863Incorrect AuthorizationThe product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.