GHSA-6c2x-gcp3-gp73 Open WebUI vulnerable to Global Knowledge Base Enumeration via knowledge-bases Meta-Collection

• PyPI open-webui: < 0.9.0 → fixed in 0.9.0

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. ```python 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 | | Confidentiality | Low (L) | Discloses KB metadata (IDs, names, descriptions) across all users | | Integrity | None (N) | No direct data modification | | Availability | None (N) | No denial of service | Attack Scenario 1. Attacker (any authenticated user) sends: ``` POST /api/v1/retrieval/query/doc { "collection_name": "knowledge-bases", "query": "confidential" } ``` 2. `_validate_collection_access` does not recognize the `knowledge-bases` prefix and lets the request pass. 3. The vector search returns the most relevant documents from the meta-collection — knowledge base records including their UUIDs, names, and descriptions — across all users on the instance. 4. Attacker varies the query to enumerate more KBs: `"project"`, `"internal"`, `"private"`, etc. 5. Attacker now has a full target list for subsequent attacks (destruction, poisoning, content extraction). Impact • Information disclosure: KB names and descriptions may reveal sensitive project names, internal initiatives, or user activities • Enabler for other attacks: Unlocks the following findings by supplying the required target UUIDs: • KB destruction/poisoning via `process/web` • Cross-user content injection via `process/file` • RAG vector search access bypass in `retrieval/utils.py` • Transforms these from theoretical (requires UUID guessing) to trivially exploitable (UUIDs enumerable) Preconditions • Attacker must have a valid user account