Affected: open-webui

Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.0, the /api/generate, /api/embed, /api/embeddings, and /api/show endpoints accept any model name from the user and forward the request to the Ollama backend without checking whether the user is authorized to access that model. These endpoints only require get_verified_user (any authenticated non-pending user) and validate that the model exists in the full unfiltered model list, but never check AccessGrants.has_access(). This vulnerability is fixed in 0.9.0.

Affected: PyPI: open-webui

# Ollama Model Access Control Bypass via /api/generate, /api/embed, /api/embeddings, and /api/show

## Affected Component

Ollama proxy endpoints missing model access control: - `backend/open_webui/routers/ollama.py` (lines 955-995, `generate_completion`) - `backend/open_webui/routers/ollama.py` (lines 835-881, `embed`) - `backend/open_webui/routers/ollama.py` (lines 891-937, `embeddings`) - `backend/open_webui/routers/ollama.py` (lines 791-820, `show_model_info`)

## Affected Versions

Current main branch (commit `6fdd19bf1`) and likely all versions with Ollama model access control support.

## Description

Four Ollama proxy endpoints accept any model name from the user and forward the request to the Ollama backend without checking whether the user is authorized to access that model. These endpoints only require `get_verified_user` (any authenticated non-pending user) and validate that the model exists in the full unfiltered model list, but never check `AccessGrants.has_access()`.

This is in direct contrast with the `/ollama/api/chat` endpoint (line 1101-1122) which correctly validates model access grants and returns 403 for unauthorized users:

```python # /api/chat (line 1101-1122) — CORRECTLY checks access if not bypass_filter and user.role == 'user': user_group_ids = {group.id for group in Groups.get_groups_by_member_id(user.id)} if not ( user.id == model_info.user_id or AccessGrants.has_access( user_id=user.id, resource_type='model'…