PHPGurukul Billing System 1.0 is vulnerable to SQL Injection in the admin/index.php endpoint. Specifically, the username parameter accepts unvalidated user input, which is then concatenated directly into a backend SQL query.
https://phpgurukul.com/billing-system-using-php-and-mysql
https://github.com/dewcode91/security-research/blob/main/CVE-2025-65380.md