CVE-2026-72811: SiYuan: SQL injection in backlink/mention search via unescaped stored and client input (publish mode): first-order (client keyword) and second-order (stored document title) breakout on read-write handle

The backlink/mention search query (kernel/model/backlink.go) concatenates stored block metadata (title, name, alias, anchor text) and the client-supplied keyword into a SQL MATCH/search statement, escaping only the double-quote character (") and not the single quote ('). A single quote in either the client keyword or in stored document metadata breaks out of the string literal. The query runs on the main read-write siyuan.db handle through a statement-stacking-capable driver.

This yields two vectors:

• First-order: a client-supplied keyword containing ' injects directly. This path is reachable by an anonymous reader on the publish surface.
• Second-order: a document whose title/name/alias contains ' is stored safely (indexing uses parameterized inserts) but detonates when that stored value is later concatenated into the backlink query including on another user’s kernel that has ingested the malicious document.