{keyword}) Union All Select Null,null,null,null,null-- Zkhd May 2026

The string you provided is a designed to discover the number of columns in a database table. Breakdown of the Payload

: This part attempts to break out of the existing SQL query structure. The closing parenthesis ) is used to "close" a likely function or subquery in the application's original code. {KEYWORD}) UNION ALL SELECT NULL,NULL,NULL,NULL,NULL-- ZkhD

: The attacker uses a specific number of NULL values to match the number of columns in the original query's SELECT statement. NULL is used because it is compatible with almost any data type (strings, integers, dates), maximizing the chance that the injected query will succeed. The string you provided is a designed to

: The number of NULL values (5 in this case) does not match the number of columns in the original table. {KEYWORD}) UNION ALL SELECT NULL,NULL,NULL,NULL,NULL-- ZkhD