GHSA-jgj3-r8hr-9pjw Open WebUI's Improper Authorization in Standard Channels Allows Message Updates with Read Permission

• PyPI open-webui: < 0.8.6 → fixed in 0.8.6

Vulnerability Description In standard channels (i.e., channels whose `channel.type` is neither `group` nor `dm`), the endpoint `POST /api/v1/channels/{channel_id}/messages/{message_id}/update` can be accessed with read permission only. When `access_control` is set to `None`, the authorization check `has_access(..., type="read")` evaluates to `True`, allowing users who are not the message owner to update messages. As a result, unauthorized modification of other users’ messages is possible. --- Attack Prerequisites • The attacker is an authenticated user (role `user` or higher) • The target channel is a standard channel (i.e., not `group` or `dm`) • `access_control` is `None` or allows `read` access • The attacker can obtain the target `message_id` (e.g., via the channel’s message list) Attack Scenario 1. The attacker (User B) retrieves another user’s `message_id` from the message list in a standard channel 2. The attacker sends a request to `POST /api/v1/channels/{channel_id}/messages/{message_id}/update` 3. The message authored by another user (User A) is successfully updated Potential Impact • Unauthorized modification of other users’ messages (violation of data integrity) Steps to Reproduce 1. Log in as an administrator 2. Create User A 3. Create User B 4. Log in as User A 5. Log in as User B 6. As the administrator, create a new channel 7. As User A, post a new message in the channel 8. As User B, edit User A’s message 9. Confirm that User A’s message has been modified without authorization Affected Files and Line Numbers • `backend/open_webui/routers/channels.py:1417–1460` The authorization check in `update_message_by_id` allows access with read permission • `backend/open_webui/utils/access_control.py:124–135` When `access_control=None` and `strict=True`, read access is permitted • `backend/open_webui/models/messages.py:341–358` The update logic does not enforce any message ownership check Recommended Mitigation Update the condition in `backend/open_webui/routers/channels.py:1451–1456` by changing the permission check from `read` to `write`, so that only administrators, message owners, or users with write permission can update messages. Proposed Changes • For standard channels, change the update permission requirement from `has_access(..., type="read")` to `has_access(..., type="write")` • Preserve the existing ownership check (`message.user_id == user.id`) AI Usage • Translation from Japanese to English • CWE classification and assessment • Affected Files and Line Numbers