Global Knowledge Base Enumeration via knowledge-bases Meta-Collection

Affected Component

Retrieval collection access validation:

• backend/open_webui/routers/retrieval.py (lines 2330-2355, _validate_collection_access)
• backend/open_webui/routers/retrieval.py (query endpoints, e.g. POST /query/doc)

Affected Versions

Current main branch (commit 6fdd19bf1) and likely all versions with the knowledge base subsystem.

Description

The _validate_collection_access function uses an incomplete allowlist that only enforces ownership checks for collections matching user-memory-* and file-* patterns. All other collection names pass through unchecked — including the system-level knowledge-bases meta-collection, which stores the IDs, names, and descriptions of every knowledge base on the instance.

Any authenticated user can query this meta-collection directly via the retrieval query endpoints to obtain a global index of all knowledge bases across all users.

# retrieval.py:2330-2355 — incomplete collection allowlist
def _validate_collection_access(user, collection_name, ...):
    if collection_name.startswith('user-memory-'):
        # Check user-memory ownership
        ...
    elif collection_name.startswith('file-'):
        # Check file access
        ...
    # Everything else (including "knowledge-bases") passes through unchecked

This finding is the enabler for the KB destruction (process/web), KB content injection (process/file), and RAG vector search access bypass findings — all of which require knowing a target KB's UUID. Without this enumeration, UUIDs are random and practically unguessable; with it, UUIDs across the entire instance are trivially obtained.

CVSS 3.1 Breakdown

Metric	Value	Rationale
Attack Vector	Network (N)	Exploited remotely via API call
Attack Complexity	Low (L)	Single API call
Privileges Required	Low (L)	Requires any authenticated user account
User Interaction	None (N)	No victim interaction required
Scope	Unchanged (U)	Impact within the knowledge base boundary