Summary

The Socket.IO server is configured with alwaysconnect=True (lines 78, 91 in backend/openwebui/socket/main.py) and the connect handler (line 329) never rejects unauthenticated connections. Two Ydoc event handlers have zero authentication checks, allowing unauthenticated clients to interact with collaborative document sessions.

Vulnerable Code

ydoc:awareness:update (line 741) — No auth check at all python @sio.on('ydoc:awareness:update') async def yjsawarenessupdate(sid, data): documentid = data['documentid'] userid = data.get('userid', sid) update = data['update'] # No SESSIONPOOL check, no room membership check await sio.emit( 'ydoc:awareness:update', {'documentid': documentid, 'userid': userid, 'update': update}, room=f'doc{documentid}', skipsid=sid, )

ydoc:document:leave (line 711) — No auth check at all python @sio.on('ydoc:document:leave') async def yjsdocumentleave(sid, data): documentid = data['documentid'] userid = data.get('userid', sid) # No auth check await YDOCMANAGER.removeuser(documentid=documentid, userid=sid) await sio.emit('ydoc:user:left', {'documentid': documentid, 'userid': userid}, room=f'doc{documentid}')

Root Cause: alwaysconnect=True (line 78) python sio = socketio.AsyncServer( alwaysconnect=True, # Never rejects connections ... )

The connect handler (line 329) adds authenticated users to SESSIONPOOL but never returns False or raises an exception for unauthenticated connections.

Exploitation

1. An unauthenticated attacker connects via Socket.IO (no token needed) 2. The attacker emits ydoc:awareness:update with: - documentid: a known/guessed note UUID (format: note:{uuid}) - userid: spoofed to impersonate any user - update: arbitrary awareness data (fake cursor positions, selections) 3. The fake awareness data is broadcast to all legitimate users in the document room 4. The attacker can also emit ydoc:document:leave with spoofed userid to broadcast fake ydoc:user:left events

Impact

- UI disruption: Fake cursor positions and user presence in collaborative editing sessions - User impersonation: Attacker can spoof any userid in awareness updates - Resource exhaustion: Unlimited unauthenticated WebSocket connections maintained by the server

Note: Other Ydoc handlers (ydoc:document:join, ydoc:document:update, ydoc:document:state) correctly check SESSIONPOOL membership.

Suggested Fix

1. Set alwaysconnect=False or reject unauthenticated connections in the connect handler 2. Add SESSIONPOOL checks to ydoc:awareness:update and ydoc:document:leave 3. Add room membership verification before broadcasting to document rooms

---

AI Disclosure (per Rule 11): AI (Claude) was used to assist with source code review, identifying potential vulnerability patterns, and drafting this report. The researcher directed the analysis, selected focus areas, and independently verified all findings against a running v0.8.12 Docker instance using real HTTP requests with two test accounts. The PoCs included are reproducible and were confirmed live before submission.