SiYuan before v3.7.4 fails to validate the packageName parameter in Bazaar install and uninstall endpoints, allowing authenticated administrators to perform path traversal via directory traversal sequences. Attackers with admin access can write arbitrary files to any location via install operations or recursively delete directories via uninstall operations by supplying crafted packageName values.

SiYuan versions before v3.7.4 contain a path traversal vulnerability in the Bazaar install and uninstall endpoints. The vulnerability stems from a failure to validate the packageName parameter, allowing authenticated administrators to supply crafted directory traversal sequences. Through install operations, attackers can write arbitrary files to any location on the system. Through uninstall operations, attackers can recursively delete directories. While exploitation requires admin-level authentication, the impact is severe as it allows full filesystem manipulation. A fix was introduced in SiYuan v3.7.4. The vulnerability is tracked as CVE-2026-77086 and has been referenced in both GitHub Security Advisories and VulnCheck.