SiYuan, an open-source knowledge management system, prior to version 3.7.0, improperly neutralizes input during web page generation in the renderPackageREADME function. The sanitizer used (lute engine with SetSanitize(true)) relies on a legacy event-handler blocklist that omits modern event handlers such as onpointerover and onanimationstart. These attributes are passed through unfiltered and assigned to innerHTML in the frontend without additional client-side sanitization or protective headers like Content-Security-Policy. This allows a third-party Bazaar package author to execute arbitrary JavaScript in the Administrator's authenticated session when the package README is viewed, resulting in full control over the workspace. The vulnerability is resolved in version 3.7.0.

An attacker controlling a third-party Bazaar package can execute arbitrary JavaScript in the context of an Administrator's authenticated session by exploiting the XSS vulnerability. This leads to full compromise of the SiYuan workspace, including potential data theft, manipulation, or further system compromise. The attack requires the Administrator to view and interact with the malicious package listing after granting marketplace trust consent.

This vulnerability is fixed in SiYuan version 3.7.0. Users should upgrade to version 3.7.0 or later to remediate this issue. No additional vendor advisory or patch links are provided, but upgrading to the fixed version is the recommended action. There are no indications that the vendor provides temporary fixes or that the vulnerability is mitigated by other means.