SiYuan EUVD-2026-74833

The fullTextSearchBlock endpoint must be network-reachable on the SiYuan instance; SiYuan is often bound to localhost by default but may be exposed on LAN or internet in server/publish deployments. The description states 'authenticated SQL injection', implying at least a publish token or session credential is required to invoke the endpoint - however, the CVSS 4.0 vector carries PR:N, suggesting the vendor may consider publish-mode access sufficient to count as unauthenticated. Exploitation is limited to confidentiality impact (blocks table read) and does not achieve code execution or data modification. Instances not exposed beyond localhost are not directly reachable.

The provided CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N) rates this at 8.7, but the description explicitly labels it an 'authenticated SQL injection', directly contradicting the PR:N metric. If a credential or publish token is required to reach the endpoint, real-world exploitability is lower than PR:N implies. EPSS data is absent, and no KEV listing exists, suggesting this is not currently under active mass exploitation. The confidentiality impact is genuine - a successful attacker reads the full blocks table - but integrity and availability are unaffected. The true priority depends on resolving the PR:N vs. authenticated discrepancy: if the endpoint is reachable without any token on default installs, risk is higher; if publish tokens are required, risk is moderate and bounded to authorized users who escalate their read scope.

An attacker who can reach the SiYuan API endpoint - either via the network or through a publish-mode session - sends a crafted GET or POST request to fullTextSearchBlock with method=1 and a query parameter containing a UNION SELECT payload. The injected query returns rows from the full blocks table alongside normal search results, allowing the attacker to iteratively dump all document content and metadata that the owner has not explicitly exposed via publish controls. The UNION-based pattern is well-documented and requires no special tooling beyond a standard HTTP client.