"ApiController::deletePage()" interpolates a page tag retrieved from the database into a "DELETE FROM …_links WHERE to_tag = '$tag'" query without escaping. The page tag is attacker-controlled — the "POST /api/pages/{tag}" API accepts arbitrary URL-encoded values, including single quotes, and stores them. A low-privilege authenticated user can therefore create a page whose tag is a SQL fragment, make the page non-orphaned via the standard "{{include page="…"}}" link mechanism, and then invoke the delete endpoint to execute arbitrary SQL inside the wiki database - including time-based blind data exfiltration from any table. This is a classic second-order SQL injection: the "INSERT" correctly escapes the value, so the malicious tag is stored intact and the input passes every "is this value safe to put in the database?" check; the sink is the read-back-and-reuse path, where escaping is omitted.