Daily Expenses Management System version 1.0, developed by PHP Gurukul, contains a time-based blind SQL injection vulnerability in the 'add-expense.php' page. An attacker can exploit the 'item' parameter in a POST request to execute arbitrary SQL commands in the backend database. This can be done by injecting specially crafted SQL queries that make the database perform time-consuming operations, thereby confirming the presence of the SQL injection vulnerability based on the delay in the server's response.