SiYuan: Cross-Site WebSocket Hijacking on the admin-only network proxy endpoint (`/ws/network/proxy`) via explicit `CheckOrigin: true` bypass

QFinch assessment

/ws/network/proxy is an admin-only WebSocket forward-proxy endpoint (target URL and headers fully attacker-specifiable via query parameters). Its websocket.Upgrader explicitly overrides CheckOrigin to unconditionally return true — disabling the origin validation that the gorilla/websocket library otherwise enforces by default. WebSocket handshake requests are not subject to CORS preflight at all (unlike fetch/XHR), so origin validation for WebSocket endpoints has to be done deliberately by the server; here it has been deliberately turned off instead. Combined with the endpoint's own query-parameter-driven proxy target, this is a textbook Cross-Site WebSocket Hijacking (CSWSH) primitive on a capability that amounts to an authenticated network pivot through the SiYuan kernel process.

Potential impact

If reachable (dependent on browser/cookie-attribute behavior at time of exploitation, as above), a malicious website visited by a user with an active, admin-privileged SiYuan session could open a WebSocket connection to this endpoint and direct the SiYuan kernel process to proxy arbitrary network traffic to an attacker-chosen target, effectively an authenticated SSRF/network-pivot primitive, using the victim's own machine and any network position it has (e.g., internal/localhost-only services on the victim's LAN that aren't reachable from the public internet), entirely via a drive-by visit to an unrelated website while SiYuan happens to be running.

Technical context

Route registration (admin-role-gated): The proxy target is fully attacker-controllable via query parameters, decoded and dialed directly: A malicious webpage can construct, entirely from JavaScript with no special access: WebSocket handshake requests are GET requests carrying ambient cookies exactly like any other cross-site navigation, and are not covered by CORS preflight protections at all, this is a distinct attack surface from ordinary fetch/XHR-based CSRF, and easy to overlook precisely because the usual CORS mental model doesn't apply to it. Whether this is currently exploitable in a given browser depends on the same session-cookie SameSite configuration already covered by a separate report on this repository (no explicit SameSite is set on the session cookie), but even where that provides incidental protection today, the explicit CheckOrigin: func(r http.Request) bool { return true } override removes a defense-in-depth layer that would otherwise exist automatically from the WebSocket library's own safe default, and is worth fixing independently of the cookie-attribute question.