SiYuan is a personal knowledge management system that, in versions 3.6.0 and earlier, contains an authorization bypass in the “/api/search/fullTextSearchBlock” endpoint. When the method parameter is set to 2, the API forwards the user-supplied input to SQLite as a raw SQL statement without applying any additional authentication or read‑only checks. This bypass allows any authenticated user—including those with the Reader role—to execute arbitrary SQL commands such as SELECT, DELETE, UPDATE, and DROP TABLE against the application database. The vulnerability is a clear example of improper authorization and unsafe SQL execution, corresponding to CWE‑863 and CWE‑89.

Affected product: SiYuan by Siyuan‑Note. Vulnerable versions are 3.6.0 and all earlier releases. The issue was fixed in version 3.6.1, so any deployment using 3.6.0 or older is susceptible.

With a CVSS score of 9.8, the vulnerability is considered critical. The EPSS score is below 1% and it is not listed in the CISA KEV catalog, indicating that public exploitation is currently unlikely but the severity remains high. An attacker who can authenticate to the system (even with a low-privilege Reader account) can send a crafted request to the search endpoint to run arbitrary SQL statements, which could lead to data loss, integrity compromise, or denial of service. The attack vector is network based, requiring that the attacker has network access to the API and a valid authenticated session.