SiYuan versions before 3.7.4 contain a cross-site request forgery vulnerability in the session-cookie authentication branch of CheckAuth() that lacks Origin/Referer validation and sets no explicit SameSite attribute on session cookies. Attackers can craft malicious web pages that perform unauthorized actions on behalf of authenticated users by submitting requests with valid session cookies, relying on browser default SameSite policies rather than server-enforced protections.