Stale Admin Role in Socket.IO Session Pool Enables Post-Demotion Cross-User Note Access

Affected Component

• backend/open webui/socket/main.py (lines 330-351, connect handler — role snapshotted into SESSION POOL)
• backend/open webui/socket/main.py (lines 393-398, heartbeat handler — does not refresh role)
• backend/open webui/socket/main.py (line 538, ydoc:document:join — uses cached role for admin check)
• backend/open webui/socket/main.py (line 611, document save handler — uses cached role for admin check)
• backend/open webui/routers/users.py (lines 557-633, role update — does not invalidate SESSION POOL)
• backend/open webui/routers/users.py (line 641, user delete — does not invalidate SESSION POOL)

Affected Versions

Description

# socket/main.py:330-351 — role snapshotted at connect time
async def connect(sid, environ, auth):
  user = None
  if auth and 'token' in auth:
    data = decode token(auth['token'])
    if data is not None and 'id' in data:
      user = Users.get user by id(data['id'])
    if user:
      SESSION POOL[sid] = {
        'id': user.id,
        'role': user.role,  # ← snapshotted, never refreshed
        ...
      }

# socket/main.py:393-398 — heartbeat refreshes last seen at only
async def heartbeat(sid, data):
  user = SESSION POOL.get(sid)
  if user:
    SESSION POOL[sid] = {**user, 'last seen at': int(time.time())}
    # role is carried forward unchanged

# socket/main.py:538 — admin check against cached role
if user.get('role') != 'admin' and not has access(user id, 'note', note id, 'read', db=db):
  return

Attack Scenario

1. User B is an admin and has an active browser session with a live Socket.IO connection. SESSION POOL[sid] records role='admin'.
2. Admin A demotes User B to a regular user via POST /api/v1/users/{B id}/update. The DB user.role becomes 'user'.
3. No Socket.IO disconnect, no SESSION POOL update, no token revocation event is triggered by the role change.
4. User B's client continues sending heartbeat events every few seconds; these are accepted and only refresh last seen at.
5. User B emits ydoc:document:join with document id = 'note:<victim note id>' for any note they do not own.
6. The handler at line 538 evaluates user.get('role') != 'admin' — returns False because SESSION POOL still holds the stale admin role. Access check is bypassed, User B joins the document room, receives full document state and live updates.
7. User B emits ydoc:document:update for the same note. The handler at line 611 performs the same cached-admin check, bypasses authorization, and persists attacker-controlled content to the victim's note via Notes.update note by id.

Impact

• Read access to any user's notes after admin privileges have been revoked
• Write access (content injection, overwrite) to any user's notes under the same conditions
• The stale privilege is bounded only by the attacker's willingness to keep the Socket.IO connection alive; heartbeats extend the session indefinitely
• Official admin demotion or user deletion gives a false sense of security — HTTP access is correctly revoked, but real-time collaborative access silently continues

Preconditions

• Attacker must have an active Socket.IO connection established while they held admin role
• Attacker must retain the Socket.IO session after demotion/deletion (trivial — just don't close the browser)