Report: CVE-2026-45402 - Open WebUI: Cross-User File Access via Unchecked file_id in Folder Knowledge and
CVE ID :CVE-2026-45402 Published : May 15, 2026, 8:40 p.m. | 44 minutes ago Description :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. Severity: 0.0 | NA Visit the link for more details, such as CVSS details, affected products, timeline, and more...