CVE-2026-73608: fallo crítico en siyuan-note siyuan

SiYuan's development branch (endpoint introduced by commit 9b8e8956f, not present in v3.7.3 or master, patched in v3.7.4-alpha.3) contains a missing-authorization vulnerability in the /api/av/getAttributeViewSearchTarget endpoint. The route is registered with CheckAuth only and performs no authorization checks (no CheckReadonly, no publish-access or encrypted-notebook gating). Given a database identifier taken from a published page and a keyword, an anonymous reader can query the endpoint to retrieve matching database row content, including rows that publish filters (FilterAttributeViewByPublishAccess) would otherwise withhold. No released stable version is affected.