CVE-2026-44554: Open WebUI has Knowledge Base Destruction and RAG Poisoning via Unauthorized Collection Overwrite

The POST /api/v1/retrieval/process/web endpoint accepts a user-supplied collection_name and an overwrite query parameter (default: True). It performs no authorization check on whether the calling user owns or has write access to the target collection. When overwrite=True, save_docs_to_vector_db calls VECTOR_DB_CLIENT.delete_collection() on the target collection before writing new content.

Combined with the knowledge base enumeration vulnerability (separate report), an attacker can trivially discover any user’s knowledge base UUID and then destroy or poison it.