SiYuan before version 3.7.0 has a route that does not require authentication. When an attacker calls /api/icon/getDynamicIcon with type=8 and a valid block ID, the server renders a Go template that evaluates user supplied SQL. The querySQL and queryBlocks functions execute arbitrary SELECT statements against the SQLite database, allowing the attacker to read all note content, tags, asset references, and block attributes. The flaw is a missing authentication mechanism (CWE-306) that leads to data leakage but does not provide arbitrary code execution.

The vulnerability affects the open‑source personal knowledge management system SiYuan (vendor siyuan-note:siyuan). All releases prior to 3.7.0 contain the flaw; versions 3.7.0 and newer have the issue fixed.

The CVSS score is 5.9, indicating moderate severity. EPSS data is unavailable, and the vulnerability is not listed in the CISA KEV catalog. An unauthenticated, network‑adjacent attacker who knows a valid block ID can exploit the endpoint, leveraging the missing authentication to execute SELECT queries and pull sensitive database content. The attack requires only network access to the service and knowledge of a block ID, making it feasible in environments where block IDs are discoverable.