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

: 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 discover the number of columns in a database table. Breakdown of the Payload {KEYWORD}) UNION ALL SELECT NULL,NULL,NULL,NULL,NULL-- ZkhD

: 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. : The attacker uses a specific number of

: The number of NULL values (5 in this case) does not match the number of columns in the original table. Breakdown of the Payload : This part attempts

An attacker (or security researcher) would send this payload to an application to see if it returns an error or a successful response.