Auth bypass in Open-Webui
CVE-2026-45402
Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.5, multiple endpoints accept a user-supplied file_id and attach the referenced file to a resource the caller controls (folder knowledge, knowledge-base contents) without verifying that the caller owns or has been granted access to the file. The file's content then becomes reachable through the downstream RAG / file-content paths, allowing any authenticated user to exfiltrate any other user's private file — and on the knowledge-base path, also to overwrite it — given knowledge of the file's UUID. This affects backend/open_webui/routers/folders.py (POST /api/v1/folders/{id}/update), backend/open_webui/routers/knowledge.py (add_file_to_knowledge_by_id), and backend/open_webui/routers/knowledge.py (add_files_to_knowledge_by_id_batch). This vulnerability is fixed in 0.9.5.
Vulnerability class: IDOR (Insecure Direct Object Reference)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N.
EPSS exploit prediction
EPSS: 0.004 (30.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 31st percentile — 30.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.004 · change: +0.000
Affected products
- Open-Webui — versions < 0.9.5
- Openwebui Open Webui
Weakness classification (CWE)
References
- github.com/open-webui/open-webui/security/advisories/GHSA-r472-mw7m-967f (Exploit, Mitigation, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-45402?
- CVE-2026-45402 is a high-severity vulnerability in Open-Webui, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 8.1/10. Published 2026-05-15.
- How severe is CVE-2026-45402?
- High severity. CVSS v3 base score is 8.1 out of 10.