NULL pointer dereference (denial of service) in PHP PDO via pdo_pgsql. When PDO emulated prepared statements are enabled (PDO::ATTR_EMULATE_PREPARES = true) on a PostgreSQL connection, supplying a parameter that contains an invalid multibyte sequence for the connection encoding causes libpq's escape function to return NULL. PDO's parameter parser in ext/pdo/pdo_sql_parser.re then reads the length of that NULL escaped value (ZSTR_LEN on a NULL zend_string), triggering a NULL pointer dereference and a segmentation fault that crashes the PHP worker process mid-transaction.