SiYuan before v3.7.3 Authentication Bypass via Content Endpoints

SiYuan versions before v3.7.3 contain an authentication bypass vulnerability in publish mode where content-returning endpoints getHeadingChildrenDOM, getHeading*Transaction, and getBacklinkDoc perform no password check despite protecting the primary getDoc endpoint. Anonymous attackers can retrieve full content of password-protected documents by obtaining internal block IDs from reader-accessible endpoints and calling unprotected content endpoints to bypass the password gate.