CVE-2026-70488

Name of the Vulnerable Software and Affected Versions Open WebUI versions 0.9.6 through 0.10.9

Description The sync cleanup endpoint POST /api/v1/knowledge/{id}/sync/cleanup allows a user with write access to one knowledge base to delete directories and remove file embeddings from another knowledge base. The system verifies write access for the knowledge base specified in the URL but fails to verify that the directory and file IDs provided in the request body belong to that same knowledge base. An attacker who possesses the target UUIDs for a directory or file can cause documents to be silently removed from retrieval results and break the chat-with-file functionality for targeted documents. This issue does not disclose the contents of the target knowledge base. The root cause is located in the sync knowledge cleanup function within backend/open webui/routers/knowledge.py.

Recommendations Update to version 0.11.0. As a temporary mitigation, restrict write access to knowledge bases to trusted users only.