Open WebUI has an Indirect Object Reference (IDOR) in user notes

Summary

The API /api/v1/notes/{note_id} endpoint lacks proper authorization checks, allowing authenticated users to retrieve notes belonging to other users by guessing or enumerating UUIDs. This results in unauthorized disclosure of potentially sensitive or private user data.

Details

• if notes is enabled from UI (Settings >> General >> Features >> Notes (Beta))
  • From API, attacker can access other user notes
• if notes is disabled from UI (Settings >> General >> Features >> Notes (Beta))
  • Then attacker can enable the notes from /api/config and access other user notes

PoC

• Step 1: Log in to the application as a valid user (User A). image

• Step 2: Intercept or inspect the response from the endpoint GET /api/config. image

• Step 3: Observe the field "enable_notes": false in the JSON response.

• Step 4: Manually change "enable_notes" to true using browser DevTools or by intercepting and modifying the response via a proxy like Burp Suite. (Please note, the occurrence of this API comes twice, hence modification needs to be made twice as well.) image

• Step 5: Observe the loaded frontend application; the previously hidden notes form will now be visible. image

image