CVE-2026-45262: FacturaScripts: Authenticated SQL injection in the FacturaScripts REST API filter parameter via parenthesis bypass in `Where::sqlColumn`

Live PoC verified 2026-04-30 against a stock FacturaScripts master at 127.0.0.1:8081. A scoped ApiKey with fullaccess=0 and an ApiAccess row granting allowget=1 on the clientes resource only (no other rights, no UI session, no admin) issued one GET /api/3/clientes?filter[(0)UNION%20SELECT%20...]= request and the response body contained the raw bcrypt hash of the admin user’s password ($2y$12$sLfA/XCqnjqLmYJwK.2V7eUHrHTHcQfkTYYfs1.lxX3OHrsmmkMGO) and the admin’s logkey cookie value. The leaked logkey was injected into a fresh cookie jar and GET /AdminPlugins returned 200 with the admin plugin management UI. End-to-end account takeover from a read-only token with no CSRF, no second factor, no rate-limit interaction beyond the default 5-incident IP throttle.

Core/Where.php::sqlColumn() exempts any field name that contains both ( and ) from identifier escaping. The two API filter builders (APIModel::getWhereValues and ApiAttachedFiles::getWhereValues) feed the raw request key ($_GET['filter'][$key]) straight into new DataBaseWhere($key, $value, '=', ...). When the model’s all() reaches Where::multiSqlLegacy -> Where::sql() -> Where::sqlColumn($key), the parenthesis branch returns the attacker-controlled string unmodified. The string is concatenated into WHERE <attacker> = '<value>', which an attacker can pivot to WHERE (0)UNION SELECT ... FROM users WHERE(nick='admin')-- = 'value', leaking arbitrary columns from any table.