Auth bypass in Open-Webui
CVE-2026-54009
Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.6, POST /api/chat/completions accepts an image_url.url value that, when it does NOT start with http://, https://, or data:image/, is interpreted as a file id and resolved against the global file table with no ownership check. an authenticated user can therefore set image_url.url to another user's file id, the server reads that file from disk, base64-encodes it, and injects the data URI into the LLM request. the user then prompts the LLM to describe / OCR the file and reads the content back. This vulnerability is fixed in 0.9.6.
Vulnerability class: IDOR (Insecure Direct Object Reference)
EPSS: 0.004 (32.0th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N.
Affected products
- Open-webui — versions < 0.9.6
- Openwebui Open_webui
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Exploit, Mitigation, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-54009?
- CVE-2026-54009 is a medium-severity vulnerability in Open-Webui, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 6.5/10. Published 2026-06-23.
- How severe is CVE-2026-54009?
- Medium severity. CVSS v3 base score is 6.5 out of 10.